Abstract: Optimization of land use structure consists of economic,social and ecological optimization.Applying the minds of system engineering and principles of ecology,this paper presents such thoughts as:① the optimal forest-coverage rate calculated according to the reality of a district is set as the main standard of ecological rationality in the district;② through considering the value of ecosystem services of the land with green equivalent(mainly cultivated land and grassland) and based on the rule:green equivalent,this paper introduces the area conversion between woods and crops,also between woods and grass.Sequentially the value of ecosystem services of theirs is assessed;③this paper establishes a multi-dimension controlling model of optimization of land use structure.Especially,a mathematic model of ecological optimization based on green equivalent is built.In addition,a multi-objective linear programming model for optimization of land use structure is designed.In the end,this paper tests and verifies this theory of ecological optimization based on green equivalent and the optimal forest-coverage rate with Qonghai City in Hainan Province as an example.This research is significant for rationality of land use structure and sustainable land use.