The invention relates to red lotus fruit juice and a preparation method thereof, and belongs to the field of foods. The red lotus fruit juice is prepared from main raw materials such as red lotus petals, purple yams, carrot and water according to a mass ratio of (1-5):(1-3):(1-3):100. The specific preparation method comprises the following steps: washing the red lotus petals, adding salt, sugar and honey, and mashing, so as to obtain red lotus juice; removing the peel of the purple yams and carrot, washing, dicing, adding the obtained blocks into water, well cooking thoroughly, juicing in a stirrer, and filtering to remove residues, so as to obtain purple yams and carrot juice; mixing the red lotus juice and the purple yams and carrot juice, adding the purified water, fully and uniformly mixing, performing ultra-high-pressure sterilization for 5-10 minutes, performing sterile filling, extracting air in the container, and filling inert gases, so as to obtain the finished red lotus fruit juice. The red lotus fruit juice disclosed by the invention is fragrant, sweet, fresh and cool in mouthfeel and strong in taste; moreover, the juice has nutrition of fruits and vegetables in the effect, and the raw materials co-act with one another and can achieve the effects of nourishing spleen, tonifying the kidney, clearing heat, soothing the nerves, regulating vital energy, nourishing heart and building the body.