The first and second treated sewage sludge at the sewage disposal plant was researched and analyzed by heavy metal analysis, proximate analysis, elementary analysis, and analysis of heating value of dried sewage sludge from February to October, as a basic characteristic research about sewage sludge. Also, research on optimal carbonization conditions for dried sewage sludge to utilize sewage sludge as fuel after carbonization was conducted from the viewpoint of energy recovery rate and low heating value. The results of analyzing volatile matter and fixed carbon in dried sewage sludge were as follows. Volatile matter in primary sewage sludge was average 13%; volatile matter in secondary sewage sludge was average 11%; fixed carbon in primary sewage sludge was average 3%; fixed carbon in secondary sewage sludge was 3%. The analysis of low heating value of dried sewage sludge showed that low heating value of primary sewage sludge was 3,300∼3,900kcal/kg, and primary sewage sludge in July and August was not good as fuel due to low caloric value. Low heating value of primary sewage sludge was higher than that of secondary sludge by 500∼800 kcal/kg. The low heating value of carbonization products had a tendency to decrease due to emission of volatile organic matters and degradation of organic materials as the treatment temperature and time got higher in the carbonization process of sewage sludge. The analysis of low heating value of primary sewage sludge indicated that optimal carbonization condition was 30~60 minutes carbonization treatment at 150~250℃, and in this condition low heating value was 2,454.16 kcal/kg and energy recovery rate was 65%. For the case of Secondary sewage sludge, optimal carbonization condition was 30~60 minutes carbonization treatment at 150~250℃ as well, and in this condition low heating value was about 2,020kcal/kg and energy recovery rate was 54%.