Abstract: It is of significance to establish the time domain model of road irregularity as the excitation to vehicles in order to perform vibration analysis, platform experiment, road damage prediction and interactive vehicle-road dynamics. The harmony superposition method based on exact mathematical theory is simpler and more efficient than other general road simulation methods. Based on the statistic illustration of stochastic road, a time series sample of road is reconstructed corresponding to a single wheel and a single track as an input excitation with respect to vehicles and the resulting sample is correctly demarcated. Then, spatial correlative stochastic processes were used to simulate bi-track road unevenness, and the two processes were linked by a virtual linear system featured with a transform function consistent with the road coherent function. The time domain model including the temporal and spatial correlativity of road irregularities was developed. This modeling method is correct in theory and can be applied to simulate stochastic road with a specific spectrum and the same stochastic processes as wind, seismism, and so on.