Abstract: A demodulation method of BPSK signal based on time measurement was presented in this paper. The theory of this method was introduced, and the experiment and its results were given too. It is a noncoherent demodulation method and can be achieved by software. So, little additional hardware is needed to implement the demodulation. Moreover, a clock can be generated to synchronize output data. This method is suitable for the demodulation of middle and low speed BPSK signal with large SNR.