In this paper, a novel electromagnetic (EM) modeling method by integral equation domain decomposition method with hybrid basis functions is developed for the solution of multi- scale problems. Based on the integral equation domain decomposition method, the original multi-scale object were decomposed into several closed sub-domains and transmission condition is enforced on the touching faces to maintain the continuity of current across the interfaces. The higher order hierarchical vector basis functions and low order Rao-Wilton-Glisson (RWG) basis functions are used in different sub-domains to reduce remarkably the number of unknowns. Because the domain decomposition method provides an effective preconditioner, the convergence history will be much better than traditional method of moments (MoM). And because of the non-conformal property of the domain decomposition method, each sub-domain can be meshed independently, which enables the mesh generation be much easier than the traditional method, especially for complex multi-scale objects. Finally, some numerical results are given to validate the ability of the present method.