In the permanent magnet synchronous generator (PMSG), the DC bus voltage fluctuates up and down under the influence of the load and power grid, which greatly affects the safe and reliable work of PMSG. In order to suppress the wide range fluctuation of DC bus voltage under disturbance and enhance its anti-disturbance performance, an optimized DC bus voltage control strategy is proposed by using the improved linear active disturbance rejection control (LADRC) in the voltage outer loop. By considering factors, such as load disturbance and grid voltage mutation as the total disturbance of the system, the improved reduced-order linear expansion state observer (RLSEO) is used to estimate and compensate the total disturbance, which greatly improves the stability of DC bus voltage. Firstly, the mathematical model of grid-side converter is established. On this basis, the LADRC control based on RLESO is designed, which reduces the phase lag of the linear extended state observer (LESO) and enhances the disturbance observation accuracy of the system. Then, a lead lag correction link is added to the total disturbance channel of RLESO to reduce the noise amplification effect of RLESO. Finally, the frequency domain characteristic analysis and stability proof of the improved LADRC control strategy are carried out. The simulation results show that the control strategy proposed in the article has a better control effect on the DC bus voltage.