Spread spectrum technology has been widely used in the field of communication and satellite navigation. Traditional methods to generate simulation data have heavy computation burden, ignoring the channel factors and other issues. Considering characteristics of spread spectrum systems signals and noise, a fast and efficient method is presented to generate signals based on spreading code chip and band-limited Gaussian noise based on AR model. Compared with the conventional high-precision methods, the complexity of calculation decreased from 1GHz rate to chip rate, and maintained the flexibility of signal generation and channel factors control at the same time. This research can be used in the simulation of modern GNSS receivers.