For developing falling film evaporation device that is suitable for organic fluid cogeneration, the gas-liquid two-phase countercurrent R113 falling film was simulated by using the RNG k-ε model in the vertical tube. The flow pattern and velocity characteristics of liquid film are analyzed. The results indicate that along the longitudinal direction, the velocity increases and the tendency tends to gently. The film thickness changes from uniform to uneven. Three kinds of flow patterns are founded, which are the steady flow, the wave flow and the shock flow. In the flow process, the liquid has a shock wave but no fracture. Compared with the theoretical value, the simulation results are reliable.