Commercial building microgrid has been widely used as a typical form of microgrid, the optimal operation of which has become an important subject. The large capacity controllable load is disposed in the commercial building microgrid, the direct load control of these loads is considered, the minimum integrated operating cost is taken as the objective function, and the optimal operation model of commercial building microgrid is established.Chaos search is introduced to improve the basic gravity algorithm,and the improved gravity algorithm is used to solve the model. Finally, a simulation algorithm is used to verify the correctness and effectiveness of the proposed model. It can reduce the integrated operating cost of the system without reducing the users’comfort level, and the improved gravitational algorithm has a better performance.