The embodiment of the invention provides a blind detection method and device for an interference source, and belongs to the technical field of wireless communication. The method is applied to a receiving end, and comprises the steps of: obtaining a pre-set number of alternative synthesis constellations, and, for each alternative synthesis constellation, finding out multiple constellation points; for each alternative synthesis constellation, taking the complex number formed by the coordinates of the multiple constellation points as the parameter value of a transmission signal in a log-likelihood blind detection algorithm formula, so that a calculated result is obtained and used as a log-likelihood result corresponding to the alternative synthesis constellation; and, in the log-likelihood results of the pre-set number of alternative synthesis constellations, selecting the alternative synthesis constellation corresponding to the maximum log-likelihood result, and taking the modulation mode corresponding to the selected alternative synthesis constellation as an interference signal modulation mode. When the signal modulation mode is a high-order modulation mode, the blind detection precision of the interference source is improved; and thus, the throughput gain of the NOMA in a practical application system can be ensured.