In view of the fact that the hybrid energy storage systems of optical storage and DC microgrids are susceptible to intermittent energy input， random load perturbations， and power flow switching， which may cause the problems of bus voltage fluctuations and system power instability， a complementary sliding mode control strategy based on a finite-time observer is proposed. First， according to the high-low frequency characteristics of the hybrid energy storage elements， the current equivalent distribution of the system differential power is carried out. Then， a finite-time dilated state observer is designed to observe the total disturbance to the system， and the disturbance observations are fed into the complementary sliding-mode controller as feedforward terms to compensate for the system disturbance， ensuring that the system state reaches convergence in finite time， improving the fast and anti-disturbance performance of the system， and proving the stability of the control system according to Lyapunov theory. Finally， based on the MATLAB simulation platform， the simulation results show that the proposed control has faster response speed and better immunity to disturbances than the traditional control strategy.