Abstract: Road excitation simulation plays an important role in vehicle design industry, especially in suspension system development. The accuracy of the road signal is critical to the success of the simulation. This paper provides an optimized solution on creating a stochastic road signal simulation which is in line with industrial standard. In this paper, the signal design is based on random vibration theory with adjustable white noise power, and a Welch’s method has been implemented instead of FFT to obtain the estimated power spectral density of the signal. To achieve a better result from the simulation, a study has been spread out to work out the relationship between the variance of the parameters of Welch’s method and the performance of the simulation. Then a certain group of parameters from Welch’s method and noise power can be finalized to present an optimized fitting result comparing with the industrial standard. In a sum, the road excitation simulation that has been established through above process can provide a reliable signal that contributes to a further vehicle design.