Abstract: There are over 32 million rural families involved in the Grain for Green Project. The achievement consolidation of the project mainly depends on the attitudes of government and rural families. From the view of opportunity cost of rural families ’ deforestation for farmland reclamation, a dynamic game model about government and rural families is built in this paper. The research draws a conclusion that whether the rural families make a decision of deforestation for farmland reclamation is decided not only by the net earnings after deforestation for farmland reclamation, but also by the opportunity cost of shifting families’labour force. Finally, four suggestions are given for the achievement consolidation of the Grain for Green Project.