The moisture absorption behavior of resin lenses can cause time-dependent performance issues of the lenses.Under specific temperature and humidity conditions, the performance of the lens is in a dynamic state of change. The primary reason is that the lens absorbs moisture, generating hygroscopic stress, which causes the surface shape of the lens to deform,thereby affecting overall optical performance. To solve these problems, there are two improvement directions. Scheme one is to optimize the optical system to reduce the surface shape sensitivity, but for specific optical specifications, the adjustment space is very limited. Scheme two is to shorten the duration of the time-dependent performance and quickly restore the system's time-dependent performance. Shortening the dynamic change time requires the analysis and simulation of the moisture absorption behavior of resin lenses, and studying the relationship between the lens structure and the moisture absorption equilibrium time to provide a direction for the design of the optical system scheme. The water absorption characteristics of resin lenses fivst experimentally is tested. The results show that temperature and humidity have a significant impact on the moisture absorption rate and saturation water absorption rate. Based on the experimental data and Fick's model, a moisture absorption model of resin lenses was established and verified. Finally, the relationship between the lens structure parameters and the moisture absorption equilibrium time was studied. The results show that the specific surface area of the lens is inversely proportional to the moisture absorption equilibrium time. The larger the specific surface area, the shorter the moisture absorption equilibrium time, and the shorter the dynamic change time of the lens performance.