Demand Side Management (DSM) activities have been designed to encourage customers to modify their patterns of electricity consumption including the timing and level of electricity demand. The role of DSM has been more and more important in the point of social energy utilization on the limited resources. The objectives of DSM are generally related to load reductions and generation cost savings. This paper presents an approach to B/C analysis to evaluate the impact of DSM programs especially on the strategic conservation and the load management programs. The proposed approach embedding the existing B/C analyses is applicable to the new electricity market. Case studies show the B/C ratio and the avoided cost due to the impact of DSM programs.