1、关键部分的代码如下，我努力交代清楚了，希望能让大家看懂。

<template><KeepAlive><component ref="comp" :is="compNames[steps[compIndex].comp]" /></KeepAlive><el-button @click="prevBtn" v-show="compIndex">上一步</el-button><el-button type="primary" @click="nextBtn">{{compIndex ? '提交': '下一步'}}</el-button>
</template><script setup lang="ts">
//引入两个子组件
import onefrom './onefrom.vue'
import twoForm from './twoForm.vue'//子组件切换相关参数
const steps = [{title:'111',comp:'one',ref:'oneForm'},{title:'222',comp:'two',ref:'twoForm'}]
//当前组件索引
const compIndex = ref(0)//子组件名
type compName = {[key:string]:any
}
const compNames = shallowReactive<compName>({oneForm,twoForm})//组件设置ref="comp"
const comp = ref(null);  //点击按钮验证子组件表单
const prevBtn = () => {compIndex.value=0
}
const nextBtn = () => {if (compIndex.value == 0 && comp.value.$refs.formRef) {comp.value.$refs.formRef.validate((valid) => {if (valid) {compIndex.value = 1  //表单验证通过后切换到子组件twoForm}});}
}

2、顺便记录下父组件获取子组件数值的写法，和获取当前日期的函数。

子组件代码

<template><el-form-item label="创建时间"><el-date-pickerv-model="currentDate"type="date"/></el-form-item>
</template><script setup lang="ts">
//获取当前日期
let currentDate = computed<string>(() => {let currentDate = new Date();let year = currentDate.getFullYear();let month = currentDate.getMonth() + 1;let day = currentDate.getDate();return year + '-' + month + '-' + day;
});// 表单参数
const initFormData = reactive<formulaForm>({id: null,name: undefined,createTime: currentDate.value
})//将表单参数暴露给父组件
defineExpose({initFormData
})
</script>

父组件接收参数

</template><component ref="comp" :is="compNames[steps[compIndex].comp]" /><el-button @click="Btn">获取参数</el-button>
</template><script setup lang="ts">
const Btn = () => {console.log(comp.value.initFormData)
}
</script>