In order to meet the high control stability requirements for the output of a tunable laser,a multi-loop control drive system applied to tunable lasers was designed and implemented.Firstly,in order to achieve high-stability current drive,an inner loop for current control was designed based on the principle of deep negative feedback control,and the interference of noise and current fluctuation on the Laser Diode (LD) was reduced by using integral compensation and RC filtering circuit.Secondly,in order to prevent the problem of LD power attenuation under constant current drive,an inner loop for power control was designed by using integral circuit and optical Power Diode (PD),and linear control was realized by using instrument amplifier circuit to eliminate common mode noise interference in the loop.Finally,in order to achieve real-time adjustment of drive current and output powerpositionbased PID control was applied to the outer loop of the system and together with the inner loopsa multi-loop control system was formed.The experimental results show that the stability of the current control is better than 200 ppm,the stability of the power control is better than 0.005 dB/h,and the stability of the laser wavelength is better than 1 pm/h,which can meet the high control stability requirements of the tunable laser.