This film evaporator unit that is composed of evaporator, gas-liquid separator, preheater of three components and a simple separator, evaporator is rising membrane type shell and tube heat exchanger. The evaporator has a large production capacity, high efficiency, shorter time for heating the material characteristics, applicable to the pharmaceutical, food, chemical and other industries of dilute solution concentration, the device part contacting materials adopts stainless steel, with good corrosion resistance, long durability, conform to the requirements of the drug and health