In modern VLSI circuits, metal conductors are separated by multiple planar, conformal or embedded dielectric media. Previous algorithms based on Boundary Element Method (BEM) are inefficient to extract interconnect capacitance due to the complex dielectric structures. In this paper, we present a new algorithm that combines multilayer Green's function with the equivalent charge method to efficiently deal with the complex dielectrics. The multilayer Green's function is efficient to model layered dielectric media, while the equivalent charge method is powerful to model non-planar complex dielectric. Our method can also model ground plane and reflective boundary wall. From experimental results, the new method is significantly faster than previous methods in realistic conditions, i.e., 70X speedup and 99% memory saving compared with FastCap and 2X speedup and 80% memory saving compared with PHiCap for complex dielectric structure with similar accuracy.