Different experiments were designed to assimilate encrypted sounding data into the WRF model, and a numerical simulation was conducted to investigate one precipitation event from a stratiform cloud system. Real-time four-dimensional data assimilation yielded good coordination of the background field and observational data, solving the problem of the spin-up mode to a certain extent. Assimilating the temperature into the model changed the original thermal field model and then the dynamic field, and the results of the model simulation became closer to the actual observation. After being processed by the nudging technique, the radar echo, height field, temperature, and precipitation were in reasonable agreement with the observations. However, because the sounding data were obtained from only two places, the results cannot cover the entire model domain. Moreover, the assimilation process also needs to be improved, and further studies are needed because some differences still appear between the simulated results and the actual observation data.