Abstract: In the day-ahead generation schedule, the rational allocation of spinning reserve (SR) capacity is a necessary means to ensure the safe and reliable operation of the power system. On the basis of analyzing the characteristics of the SR demand of a power grid, the applicability of the traditional reliability indexes is analyzed, and the indexes of the Tr minute power shortage expectation value (EDNSTr), the satisfaction probability non-emergency reserve (SPN) and the satisfaction degree of emergency reserve (SDE) are put forward. Based on the historical data of regional power grid, the data requirements and processing methods for the calculation of evaluating the SR capacity in the day-ahead generation schedule are analyzed. Finally, the limited value of the indexes and the SR capacity of a regional grid are evaluated by examples, and that proves the effectiveness of the proposed method in this paper.