Put the medicinal herbs into the extraction tank, add 5-10 times the solvent of the herbs such as purified water, ethanol, etc. according to the required liquid in the extraction process, first open the steam valve of the extraction tank, steam for about 1 hour, open the vacuum to draw the medicinal herbs in the extraction tank into the heater evaporator, open the secondary steam valve of the heater for heating and evaporation, open the buffer water storage tank valve and the condensate hot reflux pump to pour the liquid condensed by the secondary steam into the top spray pipe of the extraction tank through the preheater and spray it into the tank for 3-4 hours. Then close the steam valve of the extraction tank and the secondary steam valve of the heater, and open the steam valve of the heater for paste collection.