The invention discloses an adaptive pulse position modulation signal demodulation method, which comprises sampling and judgment. One is added to a pulse timeslot counter every time when sampling points are recorded for N times when the sampling points are recorded, and a sampling point counter is cleared. The method specifically comprises the steps of: sampling, sum computing, judgment made in whether an adaptive range L is finished or not, starting of adaptive processing, synchronous position control and the next adaptive processing. The method is a maximum-comparison-based judgment algorithm; and by the method, besides functions the same as that of the conventional methods are realized, the pulse position module (PPM) signal can be effectively demodulated under the condition of not setting a judgment threshold value and shortening program running time, demodulation performance is greatly improved, and theoretically, signals with energy higher than noise energy all can be accurately decoded.