In this paper, an efficient method is proposed for transmission network expansion planning in power systems. The power networks become more deregulated and competitive due to the power system liberalization. Power system planners are concerned with the quality of the optimization method to make power system planning more reasonable. As a result, transmission network expansion planning is one of important tasks in deregulated power systems. The mathematical formulation is expressed as a mixed integer problem. In this paper, a new meta-heuristic method is proposed to evaluate better solutions from a standpoint of global optimization. The proposed method is based on Scatter Search (SS) that makes use of a set of strategies to find out better solutions. To enhance the performance of the improvement and the solution combination methods of the SS strategies, GA and local search are used. The proposed method is successfully applied to sample systems.