The invention relates to the technical field of cosmetics, in particular to a body lotion and a preparation method thereof. The method comprises the steps that active materials are extracted from pumpkin seed oil, the active materials are mainly sterols, the active materials are subjected to emulsification, phytosterol is made to be nano-liposomes, an emulsifier generates the interface adsorptioneffect between water and the phytosterol, an oleophylic end stretches to the phytosterol and is combined with a nonpolar carbon end, hydrophilic hydroxyl stretches to water, finally, phytosterol molecules and the oleophylic end of the emulsifier form one part, water molecules and the hydrophilic end of the emulsifier form the other part, the emulsifier forms an interfacial film with the certain strength around the phytosterol molecules, condensation is not likely to occur during mutual collision, and then the purpose of emulsification is achieved; the whole system of the body lotion is stableand uniform, the stable persistence is achieved, the good emulsifiability can assist in strengthening the sterols cell membrane permeability, and the effects of nourishing skin, keeping moisture, preventing erythema and inhibiting skin inflammation are achieved.