Gymnodiptychus pachycheilus (248 individuals) were collected from the middle reach of Yalong River from October 2020 to May 2022 and used to study reproductive characteristics and assess its population growth potential. The results showed that the number of samples with phase-I and phase-II gonads was 66 and 143, respectively. No individual with phase-VI gonad was observed. The average gonadosomatic index (GSI) of male and female samples were (5.21±0.93)% and (4.75±0.87)%, respectively. The average egg diameter of the 24 female samples was (2.14±0.30) mm, and the spawning type of female G. pachycheilus belongs to the unimodal single spawning type. The average obsolute and relative fecundity of the female samples were (9054±2310) eggs and (6.56±0.69) eggs/g, respectively. A significant positive correlation was observed between absolute fecundity and standard length, body weight (P＜0.05). However, no significant correlation was observed between absolute fecundity, and gonad weight (P＞0.05). Of the 182 samples that could be sexed, the sex ratio was 1.49∶1(♀∶♂), and both the female and male samples presented the same minimum sexually mature age (4 years old). Furthermore, considering the constraints imposed by their biological characteristics and the detrimental impacts of habitat changes and human disturbances on population dynamics, the population growth potential of G. pachycheilus inhabiting the middle reaches of the Yalong River is limited, posing significant challenges for its future development.