Aiming at the control strategy of flyback switching power supply,the traditional fuzzy PID control algorithm is difficult to achieve good control effect. The whale optimization algorithm is used to optimize the fuzzy PID control system, the initial population in the whale algorithm is chaotic by Tent mapping, and the discussion domain in the fuzzy PID control system is optimized by chaotic whale optimization algorithm. The output stability and anti-interference ability of flyback switching power supply under this control system are improved. Based on Matlab software, modeling of flyback switching power supply is completed for simulation research. The simulation results show that the stability of flyback switching power supply under CWOA-FPID is better than that under WOA and particle swarm optimization. When the load changes from 10 Ω to 5 Ω, the control strategy proposed in this paper has significant advantages in voltage recovery time and voltage output mutation compared with the other two algorithms. It is proved that the fuzzy PID controller optimized by the improved whale algorithm can better meet the control requirements of flyback switching power supply.