In the electricity market environment， the price cleaning result of the spinning reserve has an important impact on the reliability of power generating system. A new index of expected un-served power considering spinning reserve（EUPCSR）， which is used to evaluate the reliability of power generating system in the operating phase， is presented. This index concludes all impacts on the system reliability， including the units' reliability parameters， ramp-rate， running time and cleaning result in the energy market and spinning reserve market. The viewpoint is presented that the cleaning result of spinning reserve is only a non-inferior solution to the minimization of purchase expense by using the queue method. Then the multi-objective and layered decision-making model， which includes reliability factors， is proposed to solve this problem. The genetic algorithm and the nonlinear optimization algorithm are used to solve the model. Simulations show the validity of the proposed method.