In wearable applications, traditional pneumatic artificial muscles (PAMs) cannot fully satisfy the requirements of safe and sufficient interaction with the human body. The requirements include high contraction ratio, self-contained sensing, reconfiguration, locking abilities, and avoidance of the squeezing force acting on the human tissue. In this letter, a reconfigurable self-sensing pneumatic artificial muscle (RSPAM) based on modular multi-chamber soft actuator with locking ability is developed, which provides an alternative that can satisfy all the requirements for the wearable applications. The contraction principle of the RSPAM, which includes transforming the expansion of the soft actuator into contraction by fabric winding, has an inherently high contraction ratio and completely avoids squeezing of human tissue. Self-sensing of contraction stroke based on liquid metal and locking ability based on positive pressure jamming are integrated. A driving force and contraction ratio of 70.14 N and of 71% were validated at 3 bar air pressure. Modular design of the actuator makes it possible to change the configuration by adjusting the actuator amount and the fabric length according to the application. In addition, the actuator unit can move on the fabric by itself, enabling a noteworthy self-adjustment ability for the muscle. The displacement self-sensing ability is verified through square-wave tracking experiments with closed-loop control. Finally, a preliminary test of assisting elbow movement verifies that the RSPAM can reduce 53.05% of the muscle fatigue.