The carrier frequency estimation algorithm of AM signal based on all-phase time-shift phase difference method uses special time shift number to estimate the frequency, which can not completely eliminate the phase ambiguity in the process of carrier frequency estimation. To solve this problem, this paper discusses the carrier frequency estimation algorithm of all-phase time-shift phase difference in general, and improves the carrier frequency estimation algorithm of AM signal combined with phase compression operation, and proposes a general correction method to eliminate phase ambiguity when the number of time shift L is not larger than the number of spectrum analysis points N. Simulation results show that when L=N, the carrier frequency estimation accuracy of the improved algorithm is significantly improved compared with that before the improvement, and the improved method is effective. In addition, the improved algorithm can eliminate phase ambiguity under any L≤N condition, and the storage and calculation amount required by the system can be saved by flexibly selecting L, which further improves the efficiency of carrier frequency estimation.