To improve the accuracy and efficiency of the simulation for the optical system in a Micro-electro-mechanical System (MEMS) and to overcome the difficulties in the system-level modeling of MEMS optical components, a system-level modeling method was proposed to support the co-simulation for MEMS system-level mechanical components and electrical components. First, the modeling methodology of Multi-Port-Element Network (MuPEN), the characteristics of Gaussian beam and the theory of space coordinate transformation were introduced. Then, the modeling process of a micro-mirror was given to explain the modeling method of all optical components. Finally, using the hardware description language of Verilog-A, an optical library including some typical components was established. The non-differential voltage simulation results of the system-level scanning system were compared with those of CoventorWare and results show that the scanning system in former environment can eliminate the blind area, and the maximum error is within 3%. It indicates that the proposed modeling method for optical components could work effectively and accurately, and the study is significant value to the MEMS system-level design.