A method for tracking base band frequency of high-sensitivity GPS receiver in variable gain mode includes enabling to eliminate phase estimation error caused by data modulation when carrier wave tracking loop is restrained quickly by making selection on frequency lock ring frequency detection algorithm in carrier wave tracking loop and phase-lock loop phase detection algorithm, enabling to obviously raise sensitivity of receiver and to decrease frequency tracking error by utilizing software to vary phase detector gain and frequency detector gain as well as digital control oscillator gain in carrier wave tracking loop at each stage in carrier-wave track.