Transmission expansion planning (TEP) is one of the most important parts in power systems. Restructuring of power system has changed the traditional planning objectives and introduced new challenges in the field of TEP. In this new environment, the comprehensive and precise design based on electricity market criteria in planning horizon is indispensable. In this paper a new algorithm is proposed for dynamic transmission expansion planning in deregulated environment. In this method, investment cost and operation cost are considered as market based economic criteria, and average load curtailment cost in contingencies is considered as a reliability criterion from market players' viewpoint. Congestion cost is also used as a competition index between market participants. The combination of Genetic Algorithm (GA) and fuzzy satisfying method is used for solving TEP problem. At last the proposed method has been tested on 8-bus network and IEEE 30-bus network.