Based on the tightly-coupled SINS/GPS integrated navigation model, a delay spoofing signal was applied to the GPS, and the influence of the spoofing signal on the navigation parameters was observed. The simulation results showed that, the spoofing signal can affect the performance of tightly-coupled navigation, and it is necessary to detect in real time whether the GPS signal is spoofed or not. And then, the Chi-Square verification method was applied to the GPS spoofing recognition, and the residual Chi-Square verification method and the state Chi-Square verification method were simulated and analyzed. The simulation results showed that both the two Chi-Square verification methods can effectively identify the slope and the step-type GPS spoofing signals.