Sample covariance matrix inversion was a basic operation unit in the realization of space-time antijamming algorithm, and its computation load grew rapidly with the increasing number of time taps, which directly restricted the application of space-time anti-jamming technique in GNSS (Global Navigation Satellite System) receiver. Aiming at this problem, a space-time anti-jamming algorithm based on block Toeplitz inversion was adopted into antijamming processing. By improving the estimation method of the covariance matrix, the algorithm got a sample covariance matrix both in the form of block Toeplitz matrix and Hermite matrix, and then the fast block Toeplitz inversion algorithm was applied to reduce the inversion complexity of covariance matrix of K taps from O［K³］to O［K²］. Theoretical analysis and simulation results show that when comparing with the traditional algorithm under the condition of 4 antenna elements and 15 taps, the anti-jamming performance cost of the proposed algorithm is less than 1dB, and its computation load reduction is about 2/3 times of the traditional algorithm.