ant-design-vue/components/cascader/demo/default-value.md

#### 默认值 默认值通过数组的方式指定。 #### Default value Specifies default value by an array.

<template>
  <a-cascader
    :options="options"
    @change="onChange"
    :defaultValue="['zhejiang', 'hangzhou', 'xihu']"
  />
</template>
<script>
  export default {
    data() {
      return {
        options: [
          {
            value: 'zhejiang',
            label: 'Zhejiang',
            children: [
              {
                value: 'hangzhou',
                label: 'Hangzhou',
                children: [
                  {
                    value: 'xihu',
                    label: 'West Lake',
                  },
                ],
              },
            ],
          },
          {
            value: 'jiangsu',
            label: 'Jiangsu',
            children: [
              {
                value: 'nanjing',
                label: 'Nanjing',
                children: [
                  {
                    value: 'zhonghuamen',
                    label: 'Zhong Hua Men',
                  },
                ],
              },
            ],
          },
        ],
      };
    },
    methods: {
      onChange(value) {
        console.log(value);
      },
    },
  };
</script>