The long-term safe service of wharf beam is related to the safety of the whole wharf structure，and the corrosion of steel bars caused by carbonization of concrete in inland river environment is the main reason for the strength degradation of wharf beam members. The inland river frame wharf located in the upper reaches of the Yangtze River is always in the service environment with relative humidity changes and is subjected to bending stress for a long time，which will aggravate the carbonization process of the wharf beam members and seriously threaten the durability of the overall structure of the wharf. Relying on the frame wharf structure of a typical port frame wharf structure in the upper reaches of the Yangtze River，based on the concrete carbonation model that comprehensively considers the combined effects of the changes in relative humidity and bending stress，combined with the time-varying model of the sectional area of corroded reinforcement of reinforced concrete material，the strength of corroded reinforcement，and the bearing capacity of flexural members，the time-varying probability distribution of the bending bearing capacity of the wharf beam members within the design service life of 50 years is calculated by Monte Carlo random simulation method. On this basis，the time-varying probability model of bending bearing capacity of beam members of inland river frame wharf is established through statistical analysis，which provides a theoretical basis for durability evaluation of inland river port wharf structures.