The invention discloses an AC system transient fault identification method based on MMC converter station information fusion technology, and belongs to the technical field of flexible HVDC. The object of the invention is to provide an AC system transient fault identification method based on MMC converter station information fusion technology that determines and identifies the AC circuit transient fault by a Renyi wavelet packet energy entropy and a Renyi wavelet packet time entropy algorithm. The method comprises the following steps: taking DC bus voltage and conducting the Renyi wavelet packet energy entropy operation; if a single phase grounding short-circuit fault occurred in an AC transmission line, taking ABC three-phase lower bridge arm current in the MMC converter station for DB4 wavelet packet transformation; and if a multi-phase fault occurred in the AC transmission line, taking ABC three-phase upper bridge arm current in the MMC converter station for DB4 wavelet packet transformation. According to the invention, the transient fault of the AC transmission circuit can be determined, and the transient fault of the AC transmission circuit can be determined and identified when only knowing the information of the MMC converter station and the DC bus.