Abstract: Traditional production simulation based on binary unit commitment suffers from huge computation burden and low efficiency in the long-midterm operation evaluation of large-scale regional power system. To address this problem, the paper proposed a production simulation method based on clustered unit commitment, in which the power network model was neglected in subregions, and the units was clustered by their sizes and types in respective subregions. Furthermore, the interconnection between subregions was modeled as a transportation model to roughly evaluate its influences on power system production simulation. The case study of a 3-area system based on IEEE RTS-96 system shows that the proposed approach can significantly improve the computation efficiency while ensuring the accuracy of calculation.