Accurate and fast multiphysics coupling analysis is of great significance to the design of microsystems. In this article, we propose a fast analysis method to improve the computational efficiency of the multiphysics coupling problem in 3-D microsystems. In this method, an iterative dual cell method (IDCM) is developed to deal with electro-thermal coupling problems, and the superposition principle is used to calculate thermal stress. The comparison between the proposed method and the finite element method (FEM) shows that IDCM and superposition principle have high accuracy, and IDCM can reduce the calculation time by up to 30% than FEM. This article studies in detail the changes of temperature and stress with two types of Through silicon via arrays, (TSV) and discusses the influence of the C4-bump layout on the stress distribution. Our work demonstrated that the proposed method can quickly and accurately perform multiphysics coupling analyzes of 3-D microsystems.