Provided is a method of selecting the optimal phase sequence arrangement mode of a one-tower double-circuit transmission line. According to the method, a one-tower double-circuit transmission line detailed simulation model is established based on an ATP/EMTP simulation platform, and phase sequence arrangement modes of which the negative sequence current imbalance is less than 5% are screened out according to the change in length of transmission lines. Moreover, a one-tower double-circuit transmission line outside-the-protected-area inter-phase short circuit fault model is built, the influence of the one-tower double-circuit transmission line phase sequence arrangement mode on misjudgment of a zero sequence power directional element in a relay protection device is evaluated according to transmission lines of different lengths, preferred sorting of negative sequence imbalance and preferred sorting of relay protection are comprehensively considered, and the optimal phase sequence arrangement mode is selected out. The engineering requirement that the negative sequence current imbalance of a newly-built one-tower double-circuit transmission line project should be less than 5% is met, and the problem that a zero sequence power directional element in a line protection device malfunctions due to the mode of conductor phase sequence arrangement is solved.