Abstract: To clarify the gonadal development pattern and reproductive characteristics of Limnoperna fortunei in a large hydropower station in the mainstream of the Yangtze River, the investigation of L. fortunei was conducted from March 2024 to May 2025, along with morphological and gonadal histological observations on all specimens. The results showed that the gonadal development of L. fortunei could be divided into four consecutive stages: proliferation stage, development stage, mature stage, and degeneration stage. The average fresh weight of mature individuals was 0.791±0.441 g, significantly greater than values observed in the other three developmental stages (P<0.001). The suitable water temperature range for L. fortunei reproduction was determined to be 12.8—28.6℃, and L. fortunei is a gonochoristic species with a female-to-male sex ratio of 1.37﹕1. Individuals at the proliferation stage were observed throughout the year, accounting for an annual average proportion of 29%. The peak of gonadal maturity occurred from July to November. Individuals at the development stage were mainly detected from March to August (accounting for 24% of the total), with the highest proportion occurring from July to September. Sexually mature individuals were found throughout the year (accounting for 35%), with the reproductive peak concentrated from April to November. The degeneration stage mainly occurred from April to December (accounting for 12%). This study revealed the gonadal development characteristics and reproductive patterns of L. fortunei in a large hydropower station along the Yangtze River mainstream, which provides a fundamental biological basis for the prevention and control of biofouling caused by L. fortunei in regional hydropower projects.