The invention discloses a production method of liquid medlar. Firstly, medlar pulp is prepared, and then liquid medlar is prepared according to the following technical steps: facilitating composite hydrolysis by ultrasonic wave, filtering, or centrifugal separating, strengthening membrane separation by ultrasonic wave, filling and sterilizing, wherein, in the process of facilitating composite enzymolysis by ultrasonic wave, ultrasonic frequency is 20 to 80 kHz, and power is 50 to 300 W, and complex enzyme which is adopted is the compound of 1 part by weight of pectase, 1.5 parts by weight of proteinase and 2.5 parts by weight of cellulase; enzyme adding amount is 0.01 to 0.15% of the total material quantity, enzymolysis temperature is 40 to 65 DEG C, and enzymolysis time is from 15 to 120 minutes. In the hydrolytic process of complex enzyme, the production method of liquid medlar is promoted by ultrasonic technology, which shortens enzymolysis reaction time for 50% and reduces enzyme adding amount by 20%, so that the production method can obviously improve enzymolysis efficiency and lower production cost.