In the early form, the distillation apparatus has a simple structure, but the liquid film is thick and the efficiency is poor, the formed liquid film is thin, and the separation efficiency is high, but the falling film type structure is complicated; in order to improve the separation efficiency, it is often necessary to use multiple stages in series to realize Multi-level separation of different substances. To increase the vapor-liquid flux per unit section, short-range molecular distillation equipment should pay attention to the relationship between its vapor-liquid ratio. One of the methods to make the equipment more compact, and to increase the production strength and the processing capacity, is not to use atmospheric distillation, but to use vacuum distillation. These phenomena are avoided by reducing the pressure in the system and lowering the boiling point of the liquid. Prevent the liquid from boiling, make the distillation happen smoothly, the capillary port should be very thin; if it is too thick, too much air will enter, the liquid in the bottle will be flushed to the condenser, and the pressure will be difficult to reduce. When it is necessary to collect different fractions in the distillation without interrupting the distillation, two or more tailpipes can be used.