We studied sexual dimorphism and female reproductive trait of the Crab-eating Frogs (Fejervarya cancrivora) based on 58 (35 ♀♀ , 23 ♂♂) adults collected from National Dongzhai Harbor Mangrove Reserve in Hainan Province. We measured eleven morphological variables on all the 58 specimens and weighed clutch mass on 29 pregnant females. The smallest of snout-urostyle length (SUL) was 44.9 mm for female and 45.2 mm for male. Except for the snout length and interorbital length, all the rest morphological traits were positively related to SUL. The SUL of adult female was significantly larger than adult male, while no any difference was found on the measurements of body weight, head length, and head width between female and male. There is sexual dimorphism between male and female in body size, female is larger than male. The clutch mass was positively related to the SUL and body mass. Our data indicate that the female frogs increase reproductive output by the way of increasing their body size.