Abstract: A dual-position loop control method and system of a turntable are based on a harmonic speed reduction mechanism. The system and the method use feedbacks from two positions with the help of a first position sensor mounted on a shaft of a motor and a second position sensor mounted on an output end of a harmonic speed reducer respectively. The response is fast at the position of the shaft of the motor, and the second position sensor at the output end of the harmonic speed reducer can directly measure the position of a harmonic output end. Therefore, the influence of nonlinearity factors on the control system is reduced.