Abstract: Urban spatial growth is an important part in research of urban development. The research of rigid growth based on ecological suitability evaluation has not been paid enough attention. Based on the fragility and the uniqueness of the ecological environment of plateau mountains, the research selected indicators, such as topography, geology, reservoir and lakes, historical and natural reserves, land cover, to evaluate the ecological suitability of land with AHP and delimited the rigid UGB of Kunming with an area of 782.45 km2. The research came to the conclusion: ①By comparing the rigid UGB and the scope of central city spatial regulation of Kunming Master plan, which is 852.93 km2, the Master plan should formulate more stringent measures to protect the ecological environment, especially the water resources along the Dianchi Lake; ②The status quo of construction land exceeds the rigid UGB by 27.74 km2, accounting for 6.49% of the total construction land. Space for development in main urban area is limited, the maximum margin of future construction land growth is 355.21  km2, which located mainly in Chenggong District and the New Zone of Airport. It is necessary to carry out macrocontrol from a regional perspective to reduce the agglomeration of resources, industries and population in main urban area. Especially, the population size and industrial planning should be reasonably formulated according to the water supply status in Dianchi Lake basin. Following planning suggestions are proposed: ①Ecological control and integration of land use structure should be strengthened. To protect the ecological security of the ecological fragile area, ecological protection buffer zone should be established along the coast of Dianchi Lake and around the ecological sensitive area against the mountains. ②The developing sequences of urban construction should be strictly controlled, so that the internal urban renewal and the construction of new districts could be completed in phases. ③In order to ensure the background boundary of ecological security and the integrity of the ecological environment around the city, the construction land out of the rigid UGB should be transferred in stages.