A numerical control focusing circuit with variable speed is designed and implemented. Based on bi.polar transistors such as PNP and NPN, the circuit is in the operation state of an emitter follower to drive the motor.The control information from upper computer is received by FPGA to control the motor accurately. The rotatingspeed of the motor can be adjusted through adjusting analog voltage generated by DA converter. The rotating speedof the motor is kept consistent by the base control voltage of PNP and NPN generated by an analog subtracter. Simu.lation and experimental results show that the circuit is in stable operation state, has simple structure without a relay,low volume and good stability, which can be used in focusing motors of lens widely.