效果如图：

方法：

在el-form-item上添加required，里面再放一层el-form-item，设置prop，在rules填校验规则

代码实例如下：

<template>
    <div>
        <el-form :rules="rules" :model="ruleForm" ref="ruleForm" label-width="100px">
            <el-form-item label="PTZ数值" required>
                <div style="display: flex;width: 100%;">
                    <el-form-item prop="ptzP">
                        <el-input v-model.trim="form.ptzP" placeholder="P" clearable></el-input>
                    </el-form-item>
                    <el-form-item prop="ptzT" style="margin: 0 5px;">
                        <el-input v-model.trim="form.ptzT" placeholder="T" clearable></el-input>
                    </el-form-item>
                    <el-form-item prop="ptzZ">
                        <el-input v-model.trim="form.ptzZ" placeholder="Z" clearable></el-input>
                    </el-form-item>
                </div>
            </el-form-item>
            <el-form-item>
                <el-button type="primary" @click="submitForm('ruleForm')">提交</el-button>
                <el-button @click="resetForm('ruleForm')">取消</el-button>
            </el-form-item>
        </el-form>
    </div>
</template>

<script>
export default {
    data() {
        return {
            form: {
                ptzP: '',
                ptzT: '',
                ptzZ: '',
            },
            rules: {
                ptzP: [
                    {
                        required: true,
                        message: "P值不能为空",
                        trigger: ["blur", "change"]
                    }
                ],
                ptzT: [
                    {
                        required: true,
                        message: "T值不能为空",
                        trigger: ["blur", "change"]
                    }
                ],
                ptzZ: [
                    {
                        required: true,
                        message: "Z值不能为空",
                        trigger: ["blur", "change"]
                    }
                ],
            }
        }
    },
    methods: {
        submitForm(formName) {
            this.$refs[formName].validate((valid) => {
                if (valid) {
                    alert('submit!')
                } else {
                    console.log('error submit!!')
                    return false
                }
            })
        },
        resetForm(formName) {
            this.$refs[formName].resetFields()
        }
    }
}
</script>

<style lang="less" scoped></style>