The author has analyzed the ecological problems caused by city development and the comprehensive benefits of green space(e.g. ecological, social and economic benefits). The important role of green space in city sustainable development was discussed. Through benefits analysis of green space in city development in Kunming City, the author offered specific measures for green space protection in Kunming: strengthen plant management according to law; enhance nation awareness of plant protection; rationally plan city green land system;and use scientific forms of green land.