To improve the running performance of heavy-haul trains, a running optimization method for heavyhaul trains based on improved sparrow search algorithm (SSA) was proposed, considering the use of circulating air braking for long downhill descent. The force analysis of each train section was carried out, the longitudinal dynamic model of the train was constructed, and the multi- objective optimization model of the train operation curve was established; the Circle chaotic map and line requirements were used to generate the initial population, and the adaptive inertial weight factor and the SSA improved by Lévy flight strategy were used to optimize the maneuvering strategy of the train in the long downhill area. The simulation results based on the actual data of the HXD1 heavy-haul train on the Daqin Line show that the improved SSA has a significant improvement effect on the key indicators of the train in the optimization strategy, such as safety, energy saving and punctuality. This study can provide some reference for the theory of circulating air braking operation of long downhill heavy-haul trains.