The invention discloses a selection method of an alternative scheme for voltage reduction operation of a generator set. The method includes the following steps: determining a candidate scheme set for voltage reduction operation of a generator set; calculating economic indexes, line trend overload rates, voltage ratio deviations, static voltage stabilization margins, static sensitivity and short circuit current indexes of all candidate schemes; establishing an evaluation model and calculating scores of the candidate schemes; sequentially verifying the candidate schemes in terms of safety; and obtaining a final scheme for voltage reduction operation of the generator set according to the scores and verification results of the candidate schemes. The selection method of the invention comprehensively takes all alternative voltage reduction operation schemes into consideration, conducts scoring and stability determination after voltage reduction operation on the alternative voltage reduction operation schemes, and comprehensively considers the stability of a power grid before and after voltage reduction operation. Furthermore, the method exhibits good universality, and is suitable for designing various voltage reduction operation schemes.