For the sake of solving the Security Constrained Unit Commitment (SCUC) problem of intermittent renewable energy access quickly and effectively, an improved ordinal optimization algorithm which can be applied to solve the uncertain SCUC problem is proposed on the basis of existing constrained ordinal optimization. In order to solve the crude model and precise model, discrete variable identification strategy and effective security constraint reduction strategy are respectively adopted. Compared to the traditional method, this modified ordinal optimization algorithm gives full play to the traditional ordinal optimization in computational efficiency while further enhances the compactness and reduces the computation redundancy. The correctness and effectiveness of the proposed algorithm are verified by the IEEE-118 simulation results. This work is supported by National Natural Science Foundation of China (No. 51607104).