The interleaved converter has may advantages such as low power losses and small output current ripple. The output current ripple of interleaved converter is the key parameter for the filter inductor design and the overall converter optimization. In this paper, the output current ripple behavior of interleaved Buck converter is analyzed, both in CCM and DCM. Further, a simplified numerical method for the output current ripple calculation of the Buck converter in DCM is presented. The proposed method provides a straightforward calculation procedure which is easy to be programmed. Simulation and experimental results validate the effectiveness of the analysis and the calculation method.