The invention discloses a multiple-input single-output STBC communication system modulation and identification method. The method includes the steps of establishing an STBC signal model, taking flat fading channel model into consideration, combining orthogonality of time space group codes and correlation of a coding matrix, calculating theoretical value and variance of primary four-order cumulant of STBC signals to be identified, solving the primary four-order cumulant of reception signals, and solving the identification threshold based on a method of maximal likelihood ratio, and finally comparing the magnitude of the experimental value and the threshold of the primary four-order cumulant of the reception signals through a combined detection method to realize the identification purpose. The method provided in the invention satisfies the requirement for modulation identification of a multiple-input single-output STBC communication system, the identification correctness is improved, and the calculation complexity is relatively low. The method is directly applicable to a non-cooperative STBC communication system, and also applicable to corresponding software radio systems.