Taking the regional power grid as the research object, the economic profits of the investment in energy storage system are studied. Firstly, the power supply model and the economic operation model of energy storage system in regional power grid are established. The combination of heuristic adjustment strategy and hybrid particle swarm optimization algorithm is used to solve the optimization mode. Then according to the life-cycle loss rate and cost-benefit analysis of energy storage system, the economic benefits and investment costs of the energy storage system are converted into a scheduling period. The economic profits of the investment scheme are evaluated by the equivalent net income. Moreover, the case study of a regional power grid is used to verify the effectiveness of the model and algorithm. The economic benefits together with profit and loss conditions of the energy storage system investment are analyzed. The influence of two key parameters of investment unit price and electricity purchase price on the investment of energy storage system is also discussed through a sensitivity analysis case. This work is supported by Science and Technology Project of State Grid Corporation of China (No. PD71-18-011) ork Flexibility Enhancement Technology based on Distributed/Mobile Energy Storage".