class My_Tree(models.Model):
    url = models.URLField()
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children', db_index=True)
    link = models.CharField(max_length=255, blank=True)
    name = models.CharField(max_length=255, blank=True)
    # def __unicode__(self):
    #     return '{0} {1}'.format(self.url, self.name)
mptt.register(My_Tree, )

    s = My_Tree(url=item['url'], link=item['link'], name=item['name'])
        s.save()

▼My_Tree object(edit)
    ▼My_Tree object(edit)
        My_Tree object(edit)

from mptt.models import MPTTModel, TreeForeignKey
class My_Tree(MPTTModel):
    parent = TreeForeignKey(
        'self', null=True, blank=True, related_name='children')
...