Switch Mode Power Supply forms an integral component of the modern day power supply systems. Owing to multiple voltage conversion requirements, there is need for a SMPS system which not only mitigates the system harmonics but also provides an efficient and reliable power conversion. In this paper, an 18-pulse input fly-back converter based SMPS system has been proposed which intends to overcome the drawbacks associated with existing 18-pulse input power supply system, based on performance parameters and overall system cost. The proposed system has been designed, implemented and thoroughly analyzed using MATLAB Simulink. Also a comparative study with the existing system has been carried based on the obtained performance parameters.