This article summarized the current time-domain model used in building random road, proposed a way to construct any road which specified road roughness coefficient, according to the method of integrating white-noise, and proved it using pseudo-excitation method, derivates its discrete format, at the same time simulated and certificated this way. The results showed that using this method to construct the road was simple, the power spectral density of road constructed with this method was in a good agreement with the given power spectral density.