Abstract: ‍ ‍Spoofing interference presents significant challenges to navigation services in critical areas， necessitating the development of spoofing interference systems， and spoofing signal parameter estimation is an important direction for the development of the systems. When the code phase of the spoofing signal overlapped with that of the authentic signal， the multi-channel technology couldnot be used to track the spoofing and the authentic signal separately. This paper proposed a method for spoofing signal parameter estimation based on NELDER-MEAD simplex algorithm with the analysis of signal parameter space in the small delay scenario and prior information such as the shape and width of the correlation peak of GNSS signal. It used NELDER-MEAD simplex algorithm to directly search for the code phase of the signal and the least squares method to estimate the power and carrier phase. This method could accurately estimate the parameters of the spoofing signal and the authentic signal while reducing the amount of calculation. The simulation results showed that the correlation domain search number dropped more than 90% compared with the traditional MLE method. Finally， the effectiveness of this method in the actual scene was verified through wireless tests.