A modified perturbation observation method is proposed to address the shortcomings of the traditional MPPT algorithm that cannot combine tracking speed and steady-state accuracy. The method achieves accurate tracking of the maximum power point by estimating the voltage value Vref at the maximum power point in real time, using a constant voltage start and a perturbation observation method with small step size. Simulation experiments are carried out in Simulink environment, and the results show that the algorithm is simple to implement, fast in dynamic response tracking, and can improve power generation efficiency.