Land holds the function of ecological,production and living at the same time.Correspondingly,it possesses the synthetic carrying capacity of ecological-production-living spaces,and the ecological carrying capacity,production carrying capacity and living carrying capacity are mutual support and interdependence.The synthetic carrying capacity of land ecological-production-living spaces means the capacity of mutualistic symbiosis between the land resource and ecological environment,and economic and social development ability with high standard of living.It consists of a support layer and a presentation layer.The ecological carrying capacity is support layer,and the production carrying capacity and living carrying capacity are presentation layers.Thus,the synthetic carrying capacity of land ecological-production-living spaces is called "San Sheng carrying capacity" for short.The Eighteenth National Congress of the Communist Party of China claimed, "We should improve development of China's geographical space,and ensure that the space for production is used intensively and efficiently,that the living space is livable and proper in size,and that the ecological space is unspoiled and beautiful." Based on this,we analyzed the basic composition and function mechanism of the synthetic carrying capacity of land ecological-production-living spaces,and a comprehensive index system from county scale is constructed by multi-scheme comparison,which including a primary index,three secondary indexes,22 three-level indexes.The quantitative calculation method of each index was also given.At last,we proposed a system dynamics model to account and simulate the synthetic carrying capacity of land ecological-production-living spaces.This study aims at providing a scientific criterion for promoting intensive utilization of land ecology,production and living spaces,and providing methods for the land comprehensive carrying capacity monitoring and early warning in China at the county scale.