Composition of mesofauna groups in Nature Reserve of Dak Rong are diversity. A total of 34 Mesofauna groups is reported belong to 30 families and subfamilies, 14 orders, 7 classes lof 3 phyla: Mollusca , Arthropoda and Annelida. According to the result, 32 earthworm species and subspecies are new records for Nature Reserve of Dakrong, Pheretima genus was found as the most dominant comprising species of 26 species (81.25 percent). Species composition of earthworm Nature Reserve of Dakrong is more diverse than Ba Be National Park, as equal as Cat Sa National Park and less diverse than Nature Reserve of Ba Na-Nui Chua. On the other hand, the results indicated that the number and biomass of earthworm species in long-day crop land habitat are correlated inversely proportional to other mesofauna groups at the same sampling point.