The appearance of one-year precocious crabs is a severe problem during the first year culture of Chinese mitten crab (Eriocheir sinensis), but it is unclear for the growth and precocious trait of the offspring produced by the one-year precocious crabs. Therefore, this study was conducted to investigate and compare body weight, carapace length, carapace width, weight gain rate (WGR), specific growth rate (SGR), survival rate, precocious rate, yield, distribution of body weight and final average weight of juvenile Eriocheir sinensis from one-year precocious family and two-year normally mature family during the first year culture stage. The results showed that: (1) except for carapace length of male crabs at 215-day-old, despite of males or females, the juveniles from the one-year precocious families had significantly lower (P<0.05) body weight, carapace length, carapace width, WGR and SGR than the juveniles from the two-year normally mature families at 155-and 215-day-old; (2) there was no significant difference in survival rate and yield of two types of families. Although the precocious rate of male juveniles from one-year precocious families was slightly higher than that of two-year normally mature families, no female precocious crabs was found in one-year precocious families. Overall, the precocious rate of two-year normally mature families normal crabs families was about twice that of one-year precocious families; (3) the size distribution of body weight was normal for juveniles from the two types of families, and the highest proportions of body weight were concentrated on 3-6 g and 6-9g for both males and females despite of families; however, both male and female, two-year normally mature families had the higher proportion of large size crabs (body weight>6 g) and lower proportion of small size crabs (body weight<6 g) than the one-year precocious families. In conclusion, the growth performance of juveniles from two-year normally mature families was better than that of one-year precocious families during the first year culture, and the precocity rate was different for the two types of families. Therefore, the further study should be conducted to investigate the physiological mechanism and gender differences for the one-year precocity.