| In order to employ the dynamical evolution process of voided sleeper, an iterative computation method based on the vehicle track coupled system dynamics model and subgrade settlement model is proposed in this paper. Simulation results indicate that when one end of the sleeper has an initial gap between the sleeper and subgrade, the sleeper subgrade contact force at this area decreases obviously. On the other hand, the sleeper subgrade contact force at the adjacent areas increases. Therefore, the sleeper voided area expands from one end to central part. Moreover, with the increased voided area the supporting capability of the sleeper deteriorates largely and most of the train loads are shared by the other sleepers. Due to this reason, the voided degree of the sleeper trends to be stable, and most areas have a gap about 1.5 mm.