In order to ensure the sufficient operation reserve of the power grid during real-time operation and adjust the deviation of operation reserve caused by the deviation of new energy and electricity load prediction in time, an intra-day rolling scheduling optimization method considering the dynamic adjustment of operation reserve was proposed. The operation reserve deviation will be evaluated according to the current generation output of the generation unit and the rolling forecast of new energy and electricity load. Fully considering the impact of positive and negative deviations of operation reserve on power grid operation, the principle of rolling scheduling optimization adjustment with the goal of minimizing the comprehensive power purchase cost is proposed. An intra-day rolling scheduling optimization model considering dynamic adjustment of operational reserve is proposed, which fully considers the change of comprehensive power purchase cost and its adjustment amplitude to the day-ahead generation plan. The scheduling plan will be re-optimized by solving the above optimization model. Finally, a case study based on the actual data of a provincial power grid was constructed to verify the effectiveness of the proposed method. The example results show that the proposed method can avoid the large adjustment of the day-ahead plan by the rolling plan, and reduce the comprehensive power purchase cost by about 1% compared with the traditional method.