In order to reveal accumulation mechanism of different sugar components and effects on sucrose metabolism related enzyme activity by carbon ion irradiation, the dynamic changes of sucrose, fructose, glucose contents and sucrose metabolism related enzyme activity were studied in the sweet sorghum, which early-maturing mutants, KF1210-3 and KF1210-4 isolated from KFJT-CK irradiated by carbon ion beam, were used as experiment materials. The results indicated that the sucrose content of KF1210-3 and KF1210-4 were significantly increased at mature stage, the value being 147.58 mg/gFw and 135.46 mg/gFw, respectively. The activities of sucrose synthase synthesis (SSs), Sucrose-phosphate synthase(SPS) were increased significantly, while sucrose synthase cleavage (SSc), acid inverse (INVA), neutral inverse (INVN) were significantly decreased. Sucrose accumulation of the mutants resulted in synergistic action of SSs, SSc, SPS, INVN and INVA. Higher ability of the sucrose synthesis and lower sucrose hydrolysis behavior increased sucrose content of the two mutants. In brief, the promoting effect on sucrose content was induced by carbon ion irradiation in sweet sorghum, which provides theory evidence for mutation breeding and related research of sucrose metabolism.Cited