System Variable Analysis on Development Stages of Urban Agriculture in Large Cities

China’s urban agricultural development takes on stage evolution,and functional structure,customer structure,industrial organization,innovation activity,spatial form and industrial value of each stage has significant difference. Using the system variable analysis method,this paper established the urban agricultural development system including six types of functional variables. On the basis of summarizing stage characteristics,it analyzed reasons for stage characteristics focusing on four key variables,i. e. cost,efficiency,connection,and risk. Finally,it came up with recommendations for promoting China’s urban agricultural development with the aid of stage development rules.