A field survey of the overwintering planthoppers (Hemiptera: Delphacidae) associated with the rice agroecosystems in southern Yunnan was carried out during January-February in 2010 and 2011. 22 species of planthoppers were collected and identified, with one species representing the subfamily Stenocraninae and the other 21 species in Delphacinae. Nycheuma cognatum (Muir), Peregrinus maidis (Ashmead), and Pseudosogata vatrenus (Fennah) were new provincial records for Yunnan. The pest species, Sogatella furcifera (Horváth), Nilaparvata lugens (Stål), and Laodelphax striatellus (Fallén) were able to overwinter in part of the survey range. 13 species were listed to be of economic importance. Abandoned rice paddies with dense Poaceae grasses (Poaceae) were the most favorable overwintering habitat. The survey range was divided into four regions and five areas based on natural geographical characteristics. The study demonstrated that winter temperature differentiation, terrains, and habitat differences were three factors affecting planthopper diversity. Planthopper species diversity showed a reductive trend from south to north and reflected a gradient of more severe winter temperatures. In addition, planthopper diversity was influenced by smaller—scale differences in terrain and habitat, as evidenced by greater diversity in the valleys and low—altitude areas as compared to mid—mountain and Karst plain areas.