System-level simulation plays an important rule in design and development of MEMS products. In this paper

a brief introduction to the two uniform modeling and simulation approaches

i.e

using Analog/Mixed Signal Hardware Description Languages(VHDL-AMS

Verilog-A

etc.)

and equivalent electrical representation

is presented at first. Then

based on the Nodal Analysis Method of MEMS

a new approach to establish equivalent circuit model of complex MEMS is mainly discussed

which is different in essence from the conventional method based on signal-flow principle. Combined with the analysis and design of a typical integrated Microsystem

viz.

a comb-shaped electrostatic feedback micro-accelerometer

the approach is specifically illustrated and validated. Finally

aiming at their principles，features and applications

the two simulation approaches are further summarized and comparatively discussed.