diff --git a/apps/qm/migrations/0054_alter_ptest_val_xj.py b/apps/qm/migrations/0054_alter_ptest_val_xj.py
new file mode 100644
index 00000000..6adcff52
--- /dev/null
+++ b/apps/qm/migrations/0054_alter_ptest_val_xj.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.2.12 on 2025-10-10 01:32
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('qm', '0053_alter_ftest_is_ok'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='ptest',
+            name='val_xj',
+            field=models.CharField(blank=True, choices=[('S', '析晶'), ('R', '不析晶'), ('θ', '未化')], help_text=[('S', '析晶'), ('R', '不析晶'), ('θ', '未化')], max_length=10, null=True, verbose_name='析晶'),
+        ),
+    ]
diff --git a/apps/qm/models.py b/apps/qm/models.py
index 8e126806..6e524f12 100644
--- a/apps/qm/models.py
+++ b/apps/qm/models.py
@@ -445,7 +445,7 @@ class Ptest(CommonAModel):
     val_tg = models.FloatField("Tg", help_text='℃', null=True, blank=True)
     val_tf = models.FloatField("Tf", help_text='℃', null=True, blank=True)
     val_xj = models.CharField(
-        '析晶', max_length=10, default='S', choices=PTEST_XJ_VALS, help_text=list(PTEST_XJ_VALS))
+        '析晶', max_length=10, null=True, blank=True, choices=PTEST_XJ_VALS, help_text=list(PTEST_XJ_VALS))
     val_pzxs = models.FloatField(
         '膨胀系数', help_text='30-300℃', null=True, blank=True)
     val_zgwd = models.FloatField('升至最高温度', null=True, blank=True)