In order to study the characteristics of the differences in the catch specifications, gonad maturity and digestive ability of Eriocheir sinensis during the reproductive migration, samples were collected from 8 sections in the lower reaches of theYangtze River during the migration flood season from October to November 2014, and the biological investigation and digestive enzyme activity were carried out. A total of 261 samples were randomly collected, including 127 female crabs and 134 male crabs. The variation of shell width is 44.46-96.06 mm, with a mean value of (64.28 ±9.45) mm, and the body mass variation is 34.9 -312.9 g, with a mean value of (131.65 ±57.79) g. There was a significant power function correlation between shell width and body weight. The female crab relationship was y=0.000 8x^{2.859 6} (R²=0.9512), and the male crab relationship was y=0.000 4x^{3.031 5}(R²=0.960 1). The variation of gonad index (GSI) was 0.71-10.84,the mean value was 4.94 ±2.59, and the hepatopancreatic index (HSI) was 2.46-20.04,with a mean value of 7.92 ±1.89. The ratio of amylase to activity was 0.02-5.45 U/mg prot, the mean value was (0.84 ±0.76) U/mg prot, and the ratio of lipase to activity was 0.28-1.13 U/g prot, the mean value was (0.68 ±0.14) U/g prot. The activity of trypsin was changed to 117.21-78 897.26 U/mg prot, the mean value was (10 947.64 ±12 663.57) U/mg prot, and the cellulase activity was 0.74-2.59 U/g prot, the mean value was (1.32 ±0.27) U/g prot. The results showed that Eriocheir sinensis had less feeding during migration,the early stage of migration was mainly supplied by the fat stored in the hepatopancreas, while the later feeding intensity gradually increased. On the reproductive migration channel, the size of the adult crabs decreased along the river, and the male crab was generally larger than the female crabs. The hepatopancreas index and the gonadal index showed the variation characteristics, the activity of amylase and trypsin decreased and the activity of cellulase was smaller, but the activity of lipase increased gradually.