In orderto suppress the voltagefluctuation oftraction network caused byfrequentstartand stop ofurban rail trains, an active disturbance rejection controller based on improved sparrow search algorithm is designed for on-board energy storageDC-DC converter. Firstly, thefirstorderactivedisturbancerejection controlleroftheDC-DC converteris established for voltage control. Then, in order to improve the rapidity and immunity of the system , sparrow search algorithm is introduced to optimize the controller parameters. Then, aiming at the shortcomings of sparrow search algorithm thatiseasytofallintolocaloptimal, Tentchaoticsequenceand diversifiedmutationprocessing areintroduced, and a new improved operatorbased on salp swarm algorithm isproposed to improve sparrow search algorithm. Finally, the speed curve ofthe train is simulated and verified. Compared with PIcontrol, traditionalactive disturbance rejection and Sparrow search activedisturbancerejection, the voltageadjustmenttimeofthe proposed activedisturbancerejection controlleris reduced by 0.012, 0.006 and 0.003 s respectively in the start-up acceleration stage, and by 0.005 4, 0.002 5 and 0.001 5 s in the braking deceleration stage, respectively. The results show thatthe designed controller is feasible and effective.