diff --git a/hb_server/apps/mtm/migrations/0033_alter_recordformfield_rule_expression.py b/hb_server/apps/mtm/migrations/0033_alter_recordformfield_rule_expression.py
new file mode 100644
index 0000000..2f44b4f
--- /dev/null
+++ b/hb_server/apps/mtm/migrations/0033_alter_recordformfield_rule_expression.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.2.6 on 2021-11-16 02:42
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mtm', '0032_alter_recordformfield_rule_expression'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='recordformfield',
+            name='rule_expression',
+            field=models.TextField(blank=True, null=True, verbose_name='判定表达式'),
+        ),
+    ]
diff --git a/hb_server/apps/mtm/models.py b/hb_server/apps/mtm/models.py
index c3fb34f..050ff6f 100644
--- a/hb_server/apps/mtm/models.py
+++ b/hb_server/apps/mtm/models.py
@@ -154,7 +154,7 @@ class RecordFormField(CommonAModel):
     high_rule = models.IntegerField('上限规则', choices=high_rule_choices, null=True, blank=True)
     low_limit = models.FloatField('下限值', null=True, blank=True)
     low_rule = models.IntegerField('下限规则', choices=low_rule_choices, null=True, blank=True)
-    rule_expression = models.TextField('判定表达式', default='')
+    rule_expression = models.TextField('判定表达式', null=True, blank=True)
 
     class Meta:
         verbose_name = '记录表格字段'