For channel′s time variability and severe rain attenuation at Ka band when near-earth satellites transmit data, using ACM (adaptive coding and modulation) technology can make full use of link resources, and further improve data throughput relative to traditional constant coding and modulation. The design method of the near-earth satellite data transmission link with ACM mode was proposed. The data transmission link model was established under the rainfall environment, then the ACM selection mode was determined depending on the channel condition. The maximum likelihood signal to noise estimation algorithm based on pilot symbols and the moving average smoothing method were adopted at channel estimation to reduce the fluctuation of the estimated value effectively. Simulation results show that no matter on clear or rainy days, the proposed satellite data transmission link ACM mode design method can obtain high data throughput while ensuring system reliability.