The invention discloses an optimization method and system for equipment capacity configuration of a park comprehensive energy system. The optimization method comprises the following steps: acquiring comprehensive energy cost of the park comprehensive energy system; taking the minimum comprehensive energy cost as an objective function; obtaining a preset optimization constraint condition of the target function; and according to the optimization constraint condition, solving the target function by using a particle swarm algorithm and mixed integer linear programming to obtain the optimal capacity of each device of the park comprehensive energy system. The optimization method for equipment capacity configuration of a park comprehensive energy system establishes an optimization design model taking minimum comprehensive energy cost as a target, utilizes the particle swarm optimization and the mixed integer linear programming to solve the optimal equipment capacity enabling the comprehensiveenergy cost to be minimum, can effectively reduce the park energy consumption cost, and can improve the system economical efficiency.