Spoofing attack can intentionally mislead the receiver to obtain the fake position or time by utilizing the counterfeit satellite signals.Although several anti-spoofing techniques have been reported to detect and suppress spoofing attack,most of the published researches are based on antenna array.In this paper,we present a spoofing mitigation algorithm based on subspace projection which is independent with antenna and even can be utilized in single-antenna GNSS receiver.With the acquired code phases,data-bit modulation,carrier frequencies and phase of all spoofing signals,the spoofing signals’ subspace matrix can be constructed.The projection of input signals onto the spoofing signals’ subspace is the sum of the spoofing signals and the projection of the noise.Then we can use the projection as an estimate of the spoofing signals.After subtracting the estimate from the input signals,the result consists of desired authorized signals,noises and the residue error resulted from the projection operation.We also prove that the performance of this method is independent of the carrier phases and data-bit modulation of the spoofing signals under special processing constraints.Besides,the Beidou B1I signal has been tested to verify the validity of the subspace projection method.