diff --git a/colossalai/nn/optimizer/colo_optimizer.py b/colossalai/nn/optimizer/colo_optimizer.py
index 52c641594..72ac91682 100644
--- a/colossalai/nn/optimizer/colo_optimizer.py
+++ b/colossalai/nn/optimizer/colo_optimizer.py
@@ -24,12 +24,7 @@ class ColoOptimizer(optim.Optimizer):
             **optimizer_kwargs: the key-word arguments to initialize the optimizer.
 
         """
-        tensors: List[Tensor] = []
-        for value in named_params.values():
-            tensors.append(value)
-
-        self.named_params = named_params
-        self._optim = optimizer_class(tensors, *optimizer_args, **optimizer_kwargs)
+        self._optim = optimizer_class([p for n, p in named_params], *optimizer_args, **optimizer_kwargs)
         self.param_groups = self._optim.param_groups
         self.state = self._optim.state
 
@@ -68,8 +63,7 @@ class ColoOptimizer(optim.Optimizer):
         Returned state and param_groups will contain parameter keys
         instead of parameter indices like torch.optim.Optimizer.
         """
-        # TODO: implement state_dict
-        raise NotImplementedError("ColoOptimizer state_dict not implemented yet!")
+        return self._optim.state_dict()
 
     def load_state_dict(self, state_dict: Mapping[str, Any]):
         r"""Loads the ColoOptimizer state.
@@ -78,11 +72,9 @@ class ColoOptimizer(optim.Optimizer):
             state_dict (dict): ColoOptimizer state. Should be an object returned
                 from a call to :meth:`state_dict`.
         """
-        # TODO: implement load_state_dict
-        raise NotImplementedError("ColoOptimizer load_state_dict not implemented yet!")
+        self._optim.load_state_dict(state_dict)
 
     def add_param_group(self, param_group: Any):
         r"""Add a new param group
         """
-        # TODO: implement add_param_group
-        raise NotImplementedError("ColoOptimizer add_param_group not implemented yet!")
+        self._optim.add_param_group(param_group)
diff --git a/colossalai/tensor/process_group.py b/colossalai/tensor/process_group.py
index 1624638c4..f6330c2b1 100644
--- a/colossalai/tensor/process_group.py
+++ b/colossalai/tensor/process_group.py
@@ -48,6 +48,7 @@ class ProcessGroup:
                  tp_degree: Optional[int] = None,
                  dp_degree: Optional[int] = None) -> None:
         if not torch.distributed.is_initialized():
+            self.is_init = False
             return
 
         assert torch.distributed.is_initialized(), f"ProcessGroup must be used after distributed initialized"
@@ -96,6 +97,7 @@ class ProcessGroup:
         self._has_cpu_groups = False
         PYTORCHPGDICT_.get(self._tp_rank_list, 'nccl')
         PYTORCHPGDICT_.get(self._dp_rank_list, 'nccl')
+        self.is_init = True
 
     def set_cpu_groups(self):
         if self.has_cpu_groups:
@@ -110,8 +112,11 @@ class ProcessGroup:
         return self._has_cpu_groups
 
     def __repr__(self):
-        return "ProcessGroup:\n\tRank: {}, World size: {}, DP degree: {}, TP degree: {}\n\tRanks in group: {}".\
-            format(self._rank, self._world_size, self._dp_degree, self._tp_degree, self._rank_list)
+        if self.is_init:
+            return "ProcessGroup:\n\tRank: {}, World size: {}, DP degree: {}, TP degree: {}\n\tRanks in group: {}".\
+                format(self._rank, self._world_size, self._dp_degree, self._tp_degree, self._rank_list)
+        else:
+            return "ProcessGroup not initialized"
 
     def __eq__(self, obj: 'ProcessGroup') -> bool:
         if not isinstance(obj, ProcessGroup):
diff --git a/tests/test_tensor/test_model.py b/tests/test_tensor/test_model.py
index 34a376891..ee5edae2c 100644
--- a/tests/test_tensor/test_model.py
+++ b/tests/test_tensor/test_model.py
@@ -33,7 +33,7 @@ def run_1d_hybrid_tp(model_name):
     if rank == 0:
         model_torch = model_builder(checkpoint=True)
         model_torch = model_torch.cuda()
-        optimizer_torch = ColoOptimizer(dict(model_torch.named_parameters()), torch.optim.SGD, lr=0.1)
+        optimizer_torch = ColoOptimizer(model_torch.named_parameters(), torch.optim.SGD, lr=0.1)
 
         # Make two models have the same init params
         for p1, p2 in zip(model.parameters(), model_torch.parameters()):
@@ -80,7 +80,7 @@ def run_1d_hybrid_tp(model_name):
     if rank == 0:
         model_torch.train()
 
-    colo_optimizer = ColoOptimizer(dict(model.named_parameters()), torch.optim.SGD, lr=0.1)
+    colo_optimizer = ColoOptimizer(model.named_parameters(), torch.optim.SGD, lr=0.1)
 
     for i, (data, label) in enumerate(train_dataloader):
 
@@ -170,7 +170,7 @@ def test_colo_optimizer():
     with ColoInitContext(lazy_memory_allocate=False, device=get_current_device()):
         model = model_builder(checkpoint=True)
 
-    colo_optimizer = ColoOptimizer(dict(model.named_parameters()), torch.optim.SGD, lr=0.1)
+    colo_optimizer = ColoOptimizer(model.named_parameters(), torch.optim.SGD, lr=0.1)
     for i, (data, label) in enumerate(train_dataloader):
         colo_optimizer.zero_grad()
         data = data.to(get_current_device())
diff --git a/tests/test_utils/test_colo_checkpoint.py b/tests/test_utils/test_colo_checkpoint.py
index 4557cfa28..13f54aefe 100644
--- a/tests/test_utils/test_colo_checkpoint.py
+++ b/tests/test_utils/test_colo_checkpoint.py
@@ -117,7 +117,7 @@ def _run_checkpoint(model_name, init_spec_func, use_ddp, use_mp_reload, test_sch
     model_reload = model_reload.cuda()
     model_reload.train()
 
-    colo_optimizer = ColoOptimizer(dict(model.named_parameters()), torch.optim.SGD, lr=0.1)
+    colo_optimizer = ColoOptimizer(model.named_parameters(), torch.optim.SGD, lr=0.1)
 
     for i, (data, label) in enumerate(train_dataloader):