The toilet suddenly collapsed, leaving Dong with a 10-centimetre wound.
He was taken to hospital and received more than 30 stitches in his buttocks.
Dong is planning to file a lawsuit against his landlord, Chen, after they failed to reach an agreement on compensation.
Chen accused Dong of using the toilet incorrectly, saying he squatted on the toilet seat rather than sitting on it.
A local lawyer said both sides had to share responsibility for the accident.