方法1

自定义表单校验

<el-form :model="Formdata" ref="formRef" :rules="nodeFormRules" label-width="100px">
	<el-form-item
	    label="年龄"
	    prop="age"
	  >
	    <el-input v-model.number="Formdata.age"></el-input>
	  </el-form-item>
</el-form>

data() {
	var checkNumber = (rule, value, callback) => {
	   // if (!value) {
	   //   return callback(new Error('年龄不能为空'));
	   // }
	   if (value && !Number.isInteger(value)) {
	     callback(new Error("请输入数字值"));
	   } else {
	     callback();
	   }
	 };
	 return{
	  nodeFormRules: {
        age: [{ validator: checkNumber, trigger: "blur" }],
      }
	}
}

方法2

只要给el-form标签加上prop和rules属性就可以了

<el-form :model="Formdata" ref="formRef" label-width="100px">
	<el-form-item
	    label="年龄"
	    prop="age"
	    :rules="[
	      { required: true, message: '年龄不能为空'},
	      { type: 'number', message: '年龄必须为数字值'}
	    ]"
	  >
	    <el-input v-model.number="Formdata.age"></el-input>
	  </el-form-item>
</el-form>

注意：
el-form标签的prop属性的值必须得和input框v-model绑定的值一致，否则校验无效

其他问题

一打开表单 还没开始输入数据 表单的校验就自动触发了
这就导致我的空表单出现了校验错误

解决

在表单页面mounted中 或者 打开表单页面之前 移除表单项的校验结果，即在对应位置加上如下代码：

this.$nextTick(() => {
  setTimeout(() => {
    this.$refs.formRef.clearValidate(); // 移除表单项的校验结果
  }, 10);
});

补充

<el-form :model="ruleForm" status-icon :rules="rules" ref="ruleForm" label-width="100px" class="demo-ruleForm">
  <el-form-item label="密码" prop="pass">
    <el-input type="password" v-model="ruleForm.pass" autocomplete="off"></el-input>
  </el-form-item>
  <el-form-item label="确认密码" prop="checkPass">
    <el-input type="password" v-model="ruleForm.checkPass" autocomplete="off"></el-input>
  </el-form-item>
  <el-form-item label="年龄" prop="age">
    <el-input v-model.number="ruleForm.age"></el-input>
  </el-form-item>
  <el-form-item>
    <el-button type="primary" @click="submitForm('ruleForm')">提交</el-button>
    <el-button @click="resetForm('ruleForm')">重置</el-button>
  </el-form-item>
</el-form>
<script>
  export default {
    data() {
      var checkAge = (rule, value, callback) => {
        if (!value) {
          return callback(new Error('年龄不能为空'));
        }
        setTimeout(() => {
          if (!Number.isInteger(value)) {
            callback(new Error('请输入数字值'));
          } else {
            if (value < 18) {
              callback(new Error('必须年满18岁'));
            } else {
              callback();
            }
          }
        }, 1000);
      };
      var validatePass = (rule, value, callback) => {
        if (value === '') {
          callback(new Error('请输入密码'));
        } else {
          if (this.ruleForm.checkPass !== '') {
            this.$refs.ruleForm.validateField('checkPass');
          }
          callback();
        }
      };
      var validatePass2 = (rule, value, callback) => {
        if (value === '') {
          callback(new Error('请再次输入密码'));
        } else if (value !== this.ruleForm.pass) {
          callback(new Error('两次输入密码不一致!'));
        } else {
          callback();
        }
      };
      return {
        ruleForm: {
          pass: '',
          checkPass: '',
          age: ''
        },
        rules: {
          pass: [
            { validator: validatePass, trigger: 'blur' }
          ],
          checkPass: [
            { validator: validatePass2, trigger: 'blur' }
          ],
          age: [
            { validator: checkAge, trigger: 'blur' }
          ]
        }
      };
    },
    methods: {
      submitForm(formName) {
        this.$refs[formName].validate((valid) => {
          if (valid) {
            alert('submit!');
          } else {
            console.log('error submit!!');
            return false;
          }
        });
      },
      resetForm(formName) {
        this.$refs[formName].resetFields();
      }
    }
  }
</script>