In order to solve the problem that the positioning system of subway relies heavily on the ground transponder, a using two-dimensional codes positioning method is proposed. Based on the high precision clock synchronization, a new data fusion algorithm was designed, the data demodulation circuit was fabricated, a high availability system with symmetric three backups was constructed, and the test method was verified. The experimental results show that the system can realize the autonomous positioning, start and stop of the train with the help of QR code, and display the train status in real time. The positioning accuracy can reach up to cm, and there is no need for the subsequent manual maintenance of the ground transponder, which saves a lot of costs. At the same time, it provides a reliable solution for the test of automatic train driving.