This paper presents a unique, fully integrated software environment, CFDACE+ MEMS, developed at CFDRC for multi-disciplinary, high-fidelity simulation of MEMS. The software has several capabilities, such as unstructured adaptive grids, polyhedral mesh elements, single and multi phase fluids, conjugate heat transfer and multi-component mixing, and chemistry modeling which makes it a unique design tool for MEMS devices. The paper also describes the overall software architecture, multi-physics field solvers, and multidisciplinary coupling procedures. CFD-Micromesh module offers fully automated geometrical modeling and meshing based on layouts and fabrication process (deposition, etching) specifications. It can import standard layout formats (CIF, GDSII), or even images (GIF, BMP), and automatically generate a 3D model. Once the mesh is generated CFDACE+ multiphysics environment automatically solves and implicitly couples field equations from several disciplines. The paper will discuss details of computational methods used for coupling FVM fluid mechanics, FEM stress/deformation , and BEM/FVM electrostatics.