To investigate the age structure and growth characteristics of the chum salmon (Oncorhynchus keta) population in the Tumen River, this study conducted age determination and measured basic biological indicators including fork length (FL) and body weight (BW) for 331 specimens collected between 2020 and 2023. Results revealed that the spawning population comprised four age groups (2+, 3+, 4+, and 5+), dominated by age-2+ and age-3+ individuals (96.37% of the total). FL ranged from 51.0 to 74.6 cm and BW ranged from 1,400 to 5,200 g. The relationship between BW and FL was expressed as: BW = 0.0159×FL2.8969, indicating isometric growth. Von Bertalanffy growth equations (VBGF) were applied to examine growth patterns among age groups and between sexes, with parameters estimated via maximum likelihood. Analysis of the residual sum of squares (ARSS) indicated no significant growth differences between sexes but revealed significant differences between the age-2+ and age-3+ groups. The size at maturity (FL50%) for females and males was 45.87 cm and 43.93 cm, respectively, with corresponding ages at maturity (T50%) of 2.00 and 1.87 years, respectively. These findings provide essential biological data for science-based management and conservation of Tumen River chum salmon.