In order to solve the problem of medical disputes caused by traditional massage training, a novel pneumatic human organ simulator was designed. A pneumatic drive system was developed and a thoracic/abdominal cavity simulator mathematical model was established. The influence of different factors such as pressure and compression displacement on the stiffness of thoracic/abdominal cavity simulator was analyzed. The experiment verified the validity of the model. The results show that the pressure of the simulator can simulate the thoracic/abdominal cavity stiffness of patients of different ages. The results provide a basis for the design of new teaching and training devices.