The invention relates to a power system unit commitment optimization method based on a branch-cut-plane algorithm. The method is characterized by comprising a first step of establishing a power system unit commitment optimization model; and a second step of obtaining a solution to the power system unit commitment optimization model by use of the branch-cut-plane algorithm. For optimization of the power system unit commitment, the problem of obtaining the solution to the unit commitment falls into two mutually independent subproblems by means of a branching process; linear programming is performed on two subdomains; in multiple branching processes, a tree structure of subproblems is generated, and the amount of calculation becomes large as the branches increase. The upper and lower bounds of an optimal target value are determined through delimitation processing so as to reduce searching times. The method is simple and flexible, is applicable to distributed parallel computing, can greatly improve the optimization performance of the model, and can rapidly, efficiently solve the unit commitment problem.