Abstract: Dinghushan (DHS) is the only nature reserve at the Tropic of Cancer in mainland China with extensive old growth monsoonal hardwood forest. We conducted preliminary surveys to the species diversity of butterflies living this reserve in July of 2006 and 2009. The total number of 240 specimen were collected, which belong to 69 species,7 families. Among these 69 species, 9 are new records for Dinghushan: Troides aeacus (Felder et Felder ), Ypthima imitans (Elwes et Edwards), Cupha erymanthis (Drury), Nacaduba kurava (Moore), Zizeeria karsandra (Moore), Astictopterus jama (Felder et Felder), Telicotta ancilla (Herrich-Schaffer), Hyarotis adrastus (Moore), and Potanthus trachalus (Mabille); Ypthima imitans is the only new record for Guangdong Province. Here we assemble a comprehensive list of the butterflies of DHS incorporating all previous records, resulting in a total of 192 species in 115 genera and 10 families, with 10 species unique to China as Neope muirheadi (Felder), Tirumala gautama (Moore), Tirumala septentrionis (Butler), Ypthima lisandra (Cramer), Ypthima praenubila (Leech), Ypthima imitans (Elwes et Edwards), Limenitis sulpitia (Cramer), Ampittia virgata (Leech), Lexias acutipenna (Chou et Li),and Prioneris thestylis (Doubleday), but only Ypthima imitans and Ypthima lisandra were found in our surveys. The study of the butterfly diversity of Dinghushan has theoretical significance and application value for sustainable development and ecotourism.