An improved time-frequency domain (TFD) method is proposed to reject interferences for Global Positioning System (GPS) receivers. The conditional TFD methods generally detect interferences through spectrum analysis, and reject them by filtering. Actually, the detection- rejection accuracy is always within the limit of the spectrum resolution. The present TFD method combines the FFT technique with an adaptive notch filter (ANF). Some initialized interference frequencies are detected first by FFT, and further updated by ANF. Numerical simulation results show that the present method could hence the anti- jamming capability of GPS receivers.