Abstract: Twenty-one isolates collected from 12 sweet potato varieties in 17 counties of Gungdong, Zhejian and Fujian provinces were compared for oxidation of three disacoharides (lactose, maltoes and cello-biose) and three hexose alcoholes (mannitol, sorbitol and dulcitol) The results indicated that there were three biotypes in isolates of Pseudomonas solanacearum from the sweet potatoes, respectively belonging to the biotype Ⅰ, Ⅲ and Ⅳ by Hayward’s classification schemes. Four isolate cultures of biotype Ⅲ were not acid-producting with the lactose, but they were pathogenic to the sweet potatoes and tested therefore were considered as the subtype of biotype Ⅲ (Biotype Ⅲ-1).