The invention discloses an INS auxiliary Beidou signal capturing method. The method includes the steps that firstly Doppler frequency generated by movements of a carrier and a satellite is calculated; the Doppler frequency is transmitted to a capturing loop of a receiver, and a carrier NCO of the loop adjusts carrier frequency; frequency mixing is conducted on intermediate frequency signals and local carrier signals to acquire in-phase signals and orthogonal signals, and the in-phase signals and the orthogonal signals correlation operations with local signals conduct respectively; correlation values acquired by each operation are stored in a cache to acquire an M*N matrix; correlation values of the in-phase branch and the orthogonal branch form a plural matrix, and whether the signals enter a tracking module or the signals are recaptured is judged until the signals are captured. The advantage of combining time domain capture and frequency domain capture is fully exerted, and a matching filter set is adopted in the matching process, so that capturing time is saved, and rapid capture of the signals in a high dynamic environment can be rapidly achieved; the correlation values of the in-phase signals and the orthogonal signals are combined in the matrix to conduct FFT conversion, so that hardware resources are saved.