Undifferentiated arthritis is also known as undefined arthritis, and its cause may be related to infection and genetic factors. Treatment of undifferentiated arthritis begins with joint protection, which requires braking or external fixation in a plaster cast during the active phase to prevent joint deformity. During the remission period, appropriate functional exercises can be performed, but in a gradual manner to prevent damage to the joint from excessive movement or weight bearing. Second, physical therapy, massage, acupuncture, etc. can be used to promote local blood circulation and reduce the symptoms of swelling and pain. Once again, medication can be used to treat the pain, such as oral anti-inflammatory and analgesic treatment with non-steroidal anti-inflammatory drugs, or oral or topical Chinese medicines to activate blood circulation, reduce swelling and pain, which can be very effective. Finally, if conservative treatment is not good enough and surgery is needed, it is recommended to go to a regular hospital and standardize the treatment under the guidance of a doctor.