The invention discloses non-boiled fresh cassava juice and a preparation method thereof, and relates to the technical field of drink processing. The preparation method comprises the following steps: cleaning fresh sweet cassava, removing the outer skin, and breaking to form granules of less than 1cm; then, putting the fresh cassava granules into a juice machine, adding boiling water, and stirring at speed of 25,000r/min to 32,000r/min for 4.5-6.5 minutes to obtain the fresh cassava juice. The fresh cassava juice retains unique flavor of the cassava, is low-sugar, low-fat, rich in a large amount of edible fibers, proteins, vitamins, amino acids, calcium, potassium, magnesium, phosphoric acid and the like, rich in nutrition and fine and smooth in mouth feel, has the effects of delaying digestive absorption, helping a human body remove intestinal tract wastes, preventing obesity, relieving constipation and the like, and is especially suitable for people with symptoms such as obesity and constipation; the fresh sweet cassava is directly used for preparing the fresh cassava juice, so that the sweet cassava market is expanded, the drink market of people is enriched, and the farmer income is increased.