Abstract: This paper indroduces the two-dimensional assembly calculation by means of ICM-interface current method. The calculation not only works out the critical Value of assemblies, K_eff, and the average flux,but also gives the spectral parameters under the condition of assembly homogenization.Two benchmark problems and some practical engineering problems were calculation with the ICM method, and the results from the calculations are in very goor agreement with the results published in foreign country and China by Monte Carlo method. The code can be used in Two-dimensional assembly calculation of Light-water reactors.