Abstract: When navigation signals, as radio interferences, affect observation in L-band, they are different from other types of interferences in communication field or radar.Using the correlation interference, traditional methods are ineffective and they lack effective evaluation indexes, too, because the power of navigation signal is normally weaker than noise power. To solve the above problems, this paper constructs a system framework of radio astronomy interference based on radio signal processing, and raises two indexes: interference suppression and signal loss based on the application of the observation data. After accurate delay compensation, this paper proposes a method to eliminate the effects of the navigation signals, using the adaptive side-lobe cancellation that suppresses the noise component of interference subspace. From the results of the simulation, conclusion can be drawn that the proposed method can effectively suppress the navigation signal in the observations, and the performance is better than that of traditional adaptive side-lobe cancellation based in feature subspace.