In order to improve the antijamming performance of global navigation satellite system receivers, a method based on the complex ANF(adaptive notch filter) was proposed to suppress narrow band interference on digital base band. The ANF was constructed by a series of the first order IIR notch filters, and the frequency parameters of all filters were updated with adaptive algorithm to detect jamming and to suppress it in real time. Simulation results show that the present method is able to suppress the jamming effectively and quickly, and the capability of signal acquisition is enhanced under condition of jamming. Moreover, a better performance than a conditional real ANF is achieved in simulation.