In this study, three strains of Clostridium butyrate were isolated from human feces, pit mud and animal intestinal contents. Which were named as Clostridium butyricum NK, SY and RX respectively. The fermentation characteristics of C. butyricum NK, SY and RX and C. tyroburicum ATCC25755 grown in synthetic medium were compared. The results showed that the growth ability of C. butyricum NK and SY were strong. C. tyroburicum had higher butyric acid, but lower lactic acid-production than C. butyricum. Compared among the three different strains of C. butyricum, C. butyricum NK had a stronger ability to produce butyric acid, with the content of 2.08 g/L in synthetic medium.