Abstract: Traditional global positioning system(GPS) signal acquisition threshold method suffers from large false alarm ratio in the condition of cross correlation interference, and thus influences weak signal acquisition. This problem was analyzed and signal acquisition detector was improved under the situation of more than one satellites existing with different signal power. Double threshold multiple detection algorithm was introduced based on the coherent correlation and non-coherent accumulation. The statistical model is non-central chi-square distributed due to cross correlation influence. A threshold calculation method was put up in the weak signal detection based on the original fixed false alarm criterion, and this threshold was considered to be the upper threshold. The original threshold was considered to be the lower threshold. An algorithm was put up considering both strong and weak signal coexistence, strong signals were acquired first and then cross correlation interference was eliminated, weak signals were acquired after that. Simulated and real data have been used to test the upper threshold, results were compared with the original method. It is proved that original method can-t detect satellite signals while new threshold works efficiently with high detection possibility and low false alarm ratio.