In this paper, we present a non-conformal, non-overlapping domain decomposition method (DDM) for the IR drop analysis of high-power integrated circuit (IC) package in which both dielectrics and non-ideal conductors coexist. The proposed non-conformal DDM starts by partitioning the composite device into inhomogeneous sub-regions. Subsequently, each sub-domain is meshed independently according to its own characteristic features. As a consequence, the troublesome mesh generation task for complex ICs can be greatly relaxed. The proposed non-conformal DDM has been applied to analyze the IR drops in the power delivery networks (PDNs) of complex ICs. Numerical results of a product-level IC package demonstrate the flexibility and potentials of the non-conformal DDM.