In recent years, Global Positioning System (GPS) spoofing is becoming more attentions in our society. How to detect GPS spoofing is a challenging work. In this paper, a GPS spoofing detection scheme is proposed based on a quadrotor unmanned aerial vehicle (UAV) model. The idea is that it compares the error between the UAV model estimator and the actual signal with a given threshold to justify whether the UAV is spoofed. Simulation is given to show that the proposed detection scheme is effective for the controlled UAV when its GPS signal is spoofed.