Abstract: In order to achieve high-precision and high-reliability control of the reaction flywheel speed, The research on the flywheel control system based on the linear Hall sensor is carried out. The principle of linear Hall sensor speed detection is introduced. A real-time velocity and position calculation algorithm is proposed. The algorithm first performs online calibration of the Hall signal; by indirectly calculating the arc sine, the efficiency of position calculation is improved, so as to realize the real-time calculation of position; By selecting the optimal Hall signal curve, the accuracy of position calculation is improved. Experimental results show that at high speed, the flywheel speed control accuracy is better than 1 r/min; at low speed, the speed control accuracy is better than 1.5 r/min, and the zero speed control accuracy reaches 0.3 r/min.