Abstract: For the 28 GHz millimeter-wave (mmWave) channel of the vehicle-to-infrastructure (V2I) in vehicular networks, we carried out a research on the channel quasi-stationary region. First, we analyzed the theoretical basis and calculation method of the quasi-stationary region. Second, the calculation of quasi-stationary region was carried out by using the correlation of power (CP) algorithm and spectral divergence (SD) algorithm. The results show the CP algorithm has low complexity and high precision, thus, it is more suitable to calculate the quasi-stationary region in the V2I communication scenario. Last, by using the CP algorithm, the results of the quasi-stationary regions were used for the new sampling intervals. Therefore, the number of sampling points of the ray tracing simulator can be reduced. Through the comparisons of channel characteristics in two simulations between original sampling number and reduced number show that, in reasonable thresholds for CP algorithm, the ray-tracing simulation can speed up, which can guarantee the accuracy of channel parameters. In addition, the results of analysis on channel characteristics will be beneficial for the simulation and design of vehicular networks at mmWave band.