Abstract: Power detection of spoofing signal is one of the most commonly used spoofing detection methods. However, the spoofing source can still achieve spoofing attack on the terminal in the ring by adjusting the power of the transmitted spoofing signal. In order to solve this problem, this paper proposes a spoofing detection method for mobile terminals based on signal power Variation. This method utilizes the essential attributes of distance difference between real satellite and deception source and terminal, it can detect spoofing jamming sources in close range effectively. In this paper, the power ratio model of mobile terminal signal is established, and on this basis, the binary hypothesis test for deception signal is given. Through theoretical analysis and simulation experiments, the validity of the proposed spoofing detection technology for mobile terminals based on signal power variation is verified. When the distance between the jammer and the terminal is less than 2000 meters, and the distance between the terminal and the terminal is more than 200 meters, the effective detection of spoofing attack can be realized under 1％ false alarm probability.