The invention belongs to the field of solid waste resource, and in particular relates to a circular inoculation method used for accelerating a fermentation process of a municipal sludge dry method. The method comprises the following steps of: fermenting a first-batch material; after inoculating exogenous granular sludge for the first time, making the material undergo a hydrolysis stage, an acidification stage and a gasification stage in turn; respectively taking a proper amount of the material in the hydrolysis stage, the acidification stage and a gas production peak stage of the first-batch material for starting hydrolysis inoculation, acidification stage inoculation and gasification stage inoculation on the next-batch material; continuing performing the fermentation process on each batch of materials after inoculating each time until discharging. In the method, the dominant strain inoculation and culture are performed in a targeted way according to microbial enrichment regularity indifferent stages of the fermentation process, which can effectively shorten transition time of each stage, promote the fermentation process, enhance ecological functions of microorganisms fermented by a dry method, achieve resource management of municipal sludge, and remarkably save equipment investment and land occupation.