The present invention provides a method and device for demodulating a message, wherein the method includes: obtaining a differential phase value corresponding to a phase value of a message to be demodulated, and a corresponding maximum likelihood ratio value, and combining the differential phase value and the obtained The maximum likelihood ratio value is stored in the cache Buffer; the first M-bit first message is obtained in the cache Buffer; when the first message fails the preset check, the M-bit message after the preset time interval After accumulating with the first message, the second message is obtained, and the text of the second message is output. Using the above scheme, on the one hand, the signal energy of the tracking output is increased by accumulation, and the signal-to-noise ratio is improved; on the other hand, the maximum likelihood The probability statistics method of random ratio improves the reliability of message judgment after accumulation, further improves the sensitivity of message decoding, and solves the problem of inaccurate positioning caused by frequent errors in message demodulation in related technologies.