This paper describes an approach to address Microgrid expansion planning problem in order to help Community Microgird (COMG) Companies to decide whether invest on installation Microgird in generation and transmission expansion planning. This approach is developed in the scope of the implementation of electricity markets that eliminated the traditional centralized planning and leads to competition of COMGs, Generation Companies (GENCOs), and Transmission Companies (TRANSCOs) for power delivery. The developed model aims at maximizing the expected revenues of COMGs, TRANSCOs, and GENCOs while ensuring the cost-effective and safe operation of the power system and incorporating uncertainty, with satisfying reliability and demand requirement. Due to the long planning horizon, distribution system is subjected to uncertainty including load growth and component outages. In this regard, the stochastic programming approach is adopted to decompose planning problem into master problem and subproblem. Master problem maximizes the profit of COMG's, GENCO's and TRANSCO's and the subproblem minimizes the short-term operation cost by considering uncertainty to enhance the resiliency of system. The numerical example is presented to analyze the effectiveness of the adding Microgrid.