The aim of this research is to select the optimal demand contract for the TOU rate customer through PSO algorithm and to drop the electricity cost for the Taiwanese industry. PSO is an alternative population-based evolutionary computation technique, also it is has more fast convergence than GA to select optimal contract capacity for TOU rate customer. Results indicated that the PSO has been highly willing to Taiwanese industry in the optimal demand contract decision. Also this research aims at measuring the benefit on TOU rate and to provide decision-makers and managers with useful load management strategies as reference.