For the further understanding of the growth and development pattern during the second year culture of pond-reared male Eriocheir sinensis, this study was designed to investigate the changes of growth parameters, gonadosomatic index (GSI), hepatosomatic index (HSI), length of chela hair and their coverage ratio on the front chela during the second year culture of male E. sinensis using culture experiment, vivisection and microscopic observation, and their relationships were further analyzed among these indices. We used the software SPSS 17.0 to analysis the experimental data, and did homogeneity of variance test by Levene. When the data did not meet the homogeneity of variance, arcsine or square root were performed for the percentage data. An analysis of variance (ANOVA) was used to test for experimental results, and Tukey s-b(K) was used for multiple comparisons. When the data was converted still not satisfied with the homogeneity of variance, we used Games-Howell nonparametric test for multiple comparisons. When P<0.05, it was significantly different and we drew charts on EXCEL. Then, the overall appearance and composition of mature reproductive system were photographed and described for the male E. sinensis. The results showed that: (1) The significant increase mainly existed during the period of March to August for the body weight (BW), carapace length (CL), carapace width (CW), and body thick (BT) during the second year culture of pond-reared male E. sinensis (Table 1), and the highest of weight gain rate (WGR) and specific growth rate (SGR) were found during April to May (Fig. 1); no significant differences were found for the body weight and the other morphological parameters during the period of September to December (Table 1). The changing trend of condition factor (CF) was shown as ‘high-low-high’, and the lowest CF was recorded at May (Table 1). (2) The gonadal development was very slow during the early stage (March to May), and it was difficult to find male gonad for this period. The testis was eye-visible from June, and the GSI increased significantly from July to November (Fig. 3 A). At July, spermatophore could be found in seminal vesicle for some crabs while the volume of accessory gland increased rapidly until August. Overall, there was a significant negative correlation between GSI and HIS (Fig. 3 B) while significant positive correlations were found between GSI and BW before the puberty molting (Fig. 4 A) as well as GSI and month (Fig. 4 B). (3) The hair length and the coverage ratio on the front chela increased significantly from April to August and no significant change was found during the other months (Fig. 6). There were significant positive correlations between hair length and coverage ratio on the front chela, hair length and BW, hair coverage ratio of chela and BW, hair length and GSI, as well as hair coverage ratio and GSI (Table 2). (4) The reproductive system of mature male E. sinensis consisted of internal and external parts, and the internal parts mainly included testis, vas deferens (divided into anterior, median and posterior parts), accessory gland, and ejaculatory duct while the external part was made of penis and petasma. The posterior vas deferens was also named as seminal vesicles because it contained plenty of spermatophores for mature males (Fig. 7). In conclusion, there were close relationships for growth, goandal development and secondary sexual characteristics during the second year culture of pond-reared male E. sinensis. The composition of male reproductive system is complex, and further study should be conducted to investigate the gonadal development pattern and staging for male E. sinensis.