The laboratory instrument rotary evaporator is mainly used for continuous distillation of a large number of volatile solvents under reduced pressure. In particular, the concentration of the extract and the distillation of the receiving liquid in the chromatographic separation can separate and purify the reaction product. The basic principle of a rotary evaporator is vacuum distillation, that is, in the case of reduced pressure, the distillation flask is continuously rotated as the solvent is distilled. The glass bottle filled with materials is rotated and uniformly heated at a constant temperature. Under the condition of connecting negative pressure, the boiling point of the material is lowered, the liquid forms a film and evaporates, and then the solvent is recovered through the glass coil condenser and the collecting bottle. It is especially suitable for the concentration, crystallization, separation and solvent recovery of heat sensitive materials.