Abstract-A credibility test method based on the features of frequency domain entropy of a phase isproposed to evaluate the blind processing results of a BPSK signal. Initially, a reference signal was constructed depending on the certain identified modulation results. By analyzing the differences of the phase of the correlation series between the observed signal and the reference signal, a reliability test problem for the BPSK signal is performed by calculating the phase spectrum entropy and comparing it with a certain threshold. Simulation results show that the proposed method can be used to verify the reliability of the blind processing results of a BPSK signal at a low signal-to-noise ratio and without a priori knowledge of the signal parameters.