The geomechanics model test is an effective technical method in solving the special complex engineering problem. In order to make the model boundary forced uniformly and the inner pressure well simulated, a digital controlling air pressure flexible loading model test system was developed, which consisted of the air pressure loading apparatus, the human-machine interactive system and the air pressure loading digital control system. The loading system made the air pressure flexible loading automatically and realized the visualization and digitalization of the loading procedure. Through the system the deformation characteristic of the deep rock mass could be revealed. By the application of the system in the salt rock underground gas storage model test the effect of changing of gas injection and production on the stability of the cavern was well simulated. The convergence deformation laws of the cavern were got on the condition of the different velocity of the gas injection and production and the different operation air pressure. The test showed that the system can simulate the inner pressure of the cavity in the geomechnical model test, and has the broad prospect in application.
