The invention discloses an SOQPSK signal demodulation method. Orthogonalization is performed on an SOQPSK signal through synchronous carriers, the I component and the Q component carrying information are separated out of the high frequency signal, then signal similarity comparison is performed by using the phase characteristics of SOQPSK to obtain the information codes of the I component and the Q component, and the obtained two sets of information codes are inputted to a decoder to acquire original codes. The tedious decoding mode in the conventional demodulation process can be simplified and the demodulation cost can be reduced.