The rising film evaporator continuously adds the material liquid to be processed from the bottom/top, and the material liquid rises/falls to a short distance. Through preheating, the material liquid begins to boil, generating bubbles in the material liquid, and then forming a gas-liquid mixture. The generated secondary steam carries the droplets and rotates upward/downward at a very high speed at the center of the tube, while the unevaporated material liquid is pulled into a thin film and rises/falls along the tube wall. The residence time is short, only a few seconds to tens of seconds, with a small liquid storage capacity, suitable for the concentration of thermosensitive materials.