The coupling interface method (CIM) proposed by Chern and Shu aims for solving elliptic complex interface problems in arbitrary dimensions under Cartesian grid. It has been proven that the method is very competitive in dealing with interface problems. In this thesis, we apply the CIM to various problems, including one dimensional moving interface problems, two dimensional diffusion equations with fixed interface, two dimensional melting problems, etc. Numerical examples are presented to test the accuracy of the method in these applications.