The invention relates to a preparation method of fructus momordicae concentrated juice. The preparation method comprises the following steps of (1) selecting materials; (2) airing the selected materials; (3) crushing the aired materials; (4) performing cooking; (5) performing filtration; and (6) performing concentration. According to the preparation method of fructus momordicae concentrated juicedisclosed by the invention, the fructus momordicae concentrated juice is wide in raw material sources and low in production cost, the prepared fructus momordicae concentrated juice is good in mouth feel, sweet in flavor, clean, sweet and refreshing, and capable of clearing heat and quenching thirst, has the effects of nourishing throat, nourishing the lungs, resolving phlegm, relieving a cough, invigorating the spleen, regulating the flow of vital energy, promoting digestion, removing food stagnation, promoting appetite, neutralizing the effect of alcoholic drinks, reducing weight, reducing blood lipid, preventing constipation and the like, and has prevention and auxiliary treatment effects on laryngopharyngitis, gastroenteritis, high blood lipid, high blood pressure and heart diseases after being drunk for a long term.