This research is to develop a weight-loss walking rehabilitation training system based on differential air pressure. The system adopted Proportion-Integral-Derivative (PID) algorithm to improve the precision of weight loss, taking MSP430F149 microprocessor of Texas Instruments as the core of pressure control system. The training software is designed based on Microsoft Visual C++ 6.0 of Microsoft. The system can provide comfortable training environment for patients with lower limb motor function impediment, and can collect electromyographic signals from patients, so as to further the scientific and normative management of the patient's information. Based on this training system, the initial bearing weight, bearing weight after maximum weight loss, and maximum weight loss percentage of 10 normal adults’ lower limbs were collected. It was found that the intraclass correlation coefficient (ICC) values were all greater than 0.6. The training system has a good reliability, which can provide scientific data for clinical weight-loss lower limb rehabilitation training.