The coding technology in Galileo system is more and more important. In this study, the spreading-spectrum technology was applied to Galileo system; the channel characteristics were discussed and simulated with the excellent stochastic and orthogonal performances. Simulation results indicated that the attenuation of channel was less than -40 dB, which had reached the specification of CDMA2000，thereby, it had simplified the complexity of Pseudo-Noise(PN) code generation, and had unified the usage of chaos sequence in the source signal and channel coding. The way of PN sequence replaced by chaos spreading-spectrum technology applied in Galileo system is feasible and practical.