The invention provides a motion capture system sensor fixing device which comprises an elastic protective sleeve. The middle of the outer surface of the elastic protective sleeve is provided with three layers of elastic fixing portions which are sequentially arranged outwards from the outer surface of the elastic protective sleeve and are sequentially reduced outwards from the outer surface of the elastic protective sleeve. A containing cavity is formed between every two adjacent layers of elastic fixing portions. An opening in one side of each containing cavity is closed through a zipper, and the other parts are closed. The fixing device is simple in structure and can be fixed at the portions of the elbow joint, the knee joint, the wrist joint, the ankle joint and the like. Due to the fact that the protective sleeve is elastic, the size of sensors in the containing cavities in the protective sleeve is slightly larger than that of the containing cavity, the sensors are fastened in the containing cavities and will not move along with movement of the joint, meanwhile, the three layers of containing cavities can adapt to sensors of different types and sizes, the adaptability is high, and the cost is low.