The embodiment of the invention provides a calculation method for generator set output in electric system recovery. The calculation method for the generator set output in the electric system recovery mainly comprises the steps that aiming at the charging subsystem formed by recovered parts in power grids, a new generator set needing to be recovered closest to the charging subsystem is searched out based on a search algorithm, and the new generator set and the charging subsystem form the whole charging system; the whole charging system is started, the minimum regulating variable of the generator active output in the whole charging system is taken as the target, and optimal active output of each generator set in the whole charging system is calculated. The calculation method for the generator set output in the electric system recovery can effectively calculate the optimal active output of each generator set in the whole charging system, the regulating time can be shortened, and the total process of the electric system recovery is accelerated. The embodiment of the calculation method for the generator set output in the electric system recovery is simple in algorithm, and compared with a traditional method, the system recovery efficiency can be improved remarkably.