The invention discloses a protective device for rheumatism patients. The device comprises a supporting part and at least two fixing parts. The supporting part comprises a first connecting rod and a second connecting rod. One end of the first connecting rod, close to t he second connecting rod, is provided with an adjusting chuck used for being hinged to the second connecting rod. The adjusting chuck is provided with a cavity, the bottom of which is equipped with an articulated shaft. The second connecting rod is hinged to the first connecting rod through the articulated shaft. The second connecting rod, corresponding to the position of a third chute, is provided with a fixed rod which matches the third chute. The top of the fixed rod is provided with a bent part. A graduated scale is arranged at the top of the adjusting chuck along the edge of the third chute. When illness of a rheumatism patient outbreaks, the protective device is used for the rheumatism patient, and the original plaster casting physiotherapy mode is changed. After a user wears the protective device, the first connecting rod and the second connecting rod can rotate relatively at will, the user can walk conveniently, and daily movement of the user is not affected.