The working principle of the rotary evaporator is to make the flask rotate at a constant speed at the most suitable speed through electronic control to increase the evaporation area. The evaporation flask is in a negative pressure state through a vacuum pump. The evaporation flask is placed in the water bath pot for constant temperature heating while rotating, and the solution in the flask is heated, diffused and evaporated in the rotating flask under negative pressure. The rotary evaporator system can be sealed and depressurized to 400 ~ 600 mm Hg; Heat the solvent in the distillation flask with a heating bath, and the heating temperature can be close to the boiling point of the solvent; At the same time, it can also rotate at a speed of 50 ~ 160 rpm, so that the solvent can form a film and increase the evaporation area. In addition, under the action of high-efficiency cooler, the hot steam can be liquefied rapidly and the evaporation rate can be accelerated.