Objective A 3D printing precise pressure device was designed specifically targeted at cambered limbs according to the requirement of postoperative rehabilitation of total knee replacement, and its effectiveness and safety was verified by finite element analysis. Method Based on lower limbs gastrocnemius muscle as the pressurized objects, the precise pressure device was designed which contained an air pressure generating module, an inflatable airbag and a 3D printing brace. Through the closed loop control algorithm, the device stably supplied different pressure values in the airbag. Distributed pressure data of the "Airbag-Skin" within contact surface was collected under different experimental conditions and imported into biomechanical simulation software which combined CT images to reconstruct three-dimensional model of the leg mechanics. Finally, effective compression area fraction and the joint micro-motion angle under each condition was obtained, thereby verified the effectiveness and safety of the system. Result Using general preferred 4cm size offset and four-barrel airbag configurations, the knee joint micro-motion angles were 5.3°, 6.1°, 7.2°, 9.5°, 10.6°，which simulated at different airbag pressure values of 40, 50, 60, 70, 80mmHg (1 mmHg=0.133 kPa), respectively. The effective compression area fraction can be up to 90.8%～95.2%. Conclusion On the condition of the preferred embodiment, the dynamic range of joint micro-motion angle and the effective compression area fraction caused by different airbag pressure values were the best and met the design requirements of effectiveness and safety. The results can contribute to analyzing the compression system’s influence on limbs biomechanics. Besides, it is of great significance for rehabilitation training effectively and safely after total knee replacement.