How to maximize market revenue is one of the key issues remaining exploring for investment and operation of energy storage station. Focusing on an independently operated battery energy storage (BES), an economic operation strategy in day ahead market is presented. First, the feasibility for an independent BES to participate in electricity market is discussed through analyzing relevant policies issued in China. Then, based on market price forecast, the mathematical model of operation strategy is established with the objective of maximizing market revenues of the BES, including revenue from day ahead energy market and reserving capacity, so that charging/discharging behavior and reserved capacity in the operating day can be optimized. Case study demonstrated that with operation strategy presented market revenue of the BES can be effectively improved.