Abstract: In order to control the leaf curl disease caused by whitefly transmitted geminiviruses(WTGs),the relationship and interaction among intermediate hosts,viral vector and diseased plant were investigated,and the route of leaf curl infection to oriental tobacco in Yunnan was studied.The results showed that oriental tobacco seedlings were infected by the viruses transmitted by whitefly from intermediate hosts in late September through early November and produced disease,the symptomless infected transplants developed symptoms during field stage.In late February whitefly flied again between tobacco plants and intermediate hosts and transmitted viruses until May.When tobacco was harvested,WTGs survived on intermediate hosts and debris of diseased plants and became the origin of the repeated infection cycle in next year.Whitefly and intermediate hosts plays an important role in the infection of WTGs to oriental tobacco.