To investigate the protective role of three antioxidantsvitamin C, vitamin E and Zn（Zn2S4•7H2O）in CdCl2induced Eriocheir sinensis sperm DNA damage, single cell gel electrophoresis was used to detect the relationship between the contents of antioxidants and DNA damage. Four parameters, L tail (Tail length in arbitrary units), Tail DNA (relative % of DNA in the comet tail), TM (tail moment means integrated value of DNA density multiplied by the migration distance，L tail×Tail DNA) and OTM(Olive tail moment means the product of the distance between the center of gravity of the head and the center of gravity of the tail and percent tail DNA), were used to evaluate the DNA damage of the Eriocheir sinensis sperms which were treated by 5 mmol/ L CdCl2. The result showed that the four parameters all increased remarkably and the sperm DNA was seriously damaged by CdCl2. After that the protective effects of 3 kinds of antioxidants on CdCl2induced DNA damage were investigated. The contents of VC were 400 μmol/L,1 mmol/L, 3 mmol/L and 5 mmol/L；that of VE were 50 μmol/L,100 μmol/L,200 μmol/L and 400 μmol/L；and that of Zn were 400 μg•Ml/L,1 mg/L,2 mg/L and 4 mg/mL, respectively. The result showed that all these three antioxidants can protect 〖WTBX〗Eriocheir sinensis sperm DNA from oxidizing. The bigger the content of VE and Zn, the stronger the protective effect was. When the content of VC was 3 mmol/L, the protective effect was the best and the ratio of cell drag was comparatively low. But when the content of that was 5 mmol/L, the ratio of cell drag increased and the DNA damage became more serious. So it was concluded that the content of VC which could protect the sperm DNA from damaging was limited. Whereas the protective effect of VE and Zn had no limit of the content. Furthermore, by contrast to VC and Zn, VE appeared better protective effects with concentration of 400 μmol/L. Vitamin E and Zn possessed antagonism to CdCl2 induced DNA damage but vitamin C possessed dual nature. Vitamin E was a sort of perfect antioxidants in antagonism to CdCl2induced DNA damage. In addition, CASP is a good software to analyse comet image externally better than other analysis methods such as routine method. This research can provide methods for the research of Eriocheir sinensis feed additive, species protection, and sperm quality assessment.