Sepia esculenta as an important cephalopod resource in China，has high economic and nutritional value. This paper was based on a trawl survey of Sepia esculenta samples collected in the central part of the East China Sea（123. 0°E-127. 5°E，27. 5°N-31. 5°N）from September of the same year to March of the following year from 2017 to 2021，and analyzed their mantle length and body mass composition，gonadal development，and the first sexual maturity mantle length L₅₀. The results showed that the dominant mantle length groups of both female and male individuals in the Sepia esculenta are 81-120 mm and 81-140 mm， respectively；the dominant body mass groups are 41-280 g and 41-200 g，respectively. Individuals with low gonadal development in the Sepia esculenta grow faster than individuals with high gonadal development；and females grow faster than males. During the investigation period，the gonads developed over time；no I stage individuals were found in the group with a mantle length of over 161 mm. The results using the logistic equation and polynomial mantle length and body mass model to estimate L₅₀ are：124. 30 mm and 127. 98 mm for females，129. 18 mm and 142. 44 mm for males，respectively. The L₅₀ estimated based on the polynomial mantle length and body mass equation has a better fitting effect. The Sepia esculenta has obvious seasonal reproductive characteristics，with a breeding period of 1-3 months during the sampling period；during maturity，females transit more energy from body growth to gonadal development，and their change in growth mode is significantly earlier than males；to facilitate fishing by fishermen and ensure that all individuals have reached maturity，it is recommended that the minimum opening length of the Sepia esculenta in the central waters of the East China Sea should be greater than 142 mm.