The positionless brushless DC motor has the advantages of simple structure, good speed performance and high efficiency. It has become the best choice for horizontal well tractor. This paper introduces a set of brushless DC motor control system, gives the hardware structure of the system and brushless DC motor without Hall sensor control flow chart and the host computer communication interface protocol which solves the problem of phase lag in the case of high speed motor. Aiming at the problem that the parameters of the motor can not be monitored, the host computer monitoring program based on c# can be designed to monitor the parameters of the motor in real time. The experimental results show that the control system can make the motor run smoothly at different speeds, and can monitor the parameters of the motor in real time, suitable for the horizontal well logging and so on the motor control system requires relatively high industrial environment.