Abstract: To explore the effect of cadmium (Cd) on oogenesis of freshwater crab (Sinopotamon henanense), vitellin (Vn) and the method of Vn-ELISA was studied and established. Vn was purified from mature ovaries of S. henanense by gel filtration chromatography. Using SDS- polyacrylamide gel electrophoresis (SDS-PAGE), the molecular weight and the quantity of Vn subunit were determined. Based on the purified Vn and Vn anti-serum, the reaction parameters for an enzyme-linked immunosorbent assay (ELISA) was developed. To explore the effect of cadmium on the Vn in the ovaries, freshwater crab S. henanense were treated with 5.8 mg/L Cd for 10, 15, and 20d. The results showed that Vn was composed of three subunits (116, 66 and 45 kD). Western-blotting confirmed the polypeptides had a specific reactivity with mouse polyclonal Vn anti-serum. The optimal dilution rates of Vn anti-serum were shown to be 1:100000. According to these optimal parameters, the standard linear equation was established for the determination of Vn concentration with a valid range of 1252000 ng/mL, and qualitative detection can be 15.62 ng/mL. In verification experiments, Vn content in the ovaries showed no significant differences, and the mean coefficients of variation of inter-assay were 7.81%, suggesting that the developed ELISA of this study was precise, stable and repeatable. Moreover, Cd caused a time-dependend down-regulation of Vn level, and showed significant effects of Cd on vitellogenesis, which suggest that Cd slows down oocyte maturation and vitellogenesis in S. henanense.