Abstract: A use of extracts of roselle seeds for preparing a composition of antioxidant, anti-inflammation, anti-UVB, anti-allergy, whitening, moisturizing, and anti-wrinkle, wherein the extracts of the roselle seeds comprise lauric, palmitic, linoleic, oleic, or stearic acids; and a method for preparing the extracts of the roselle seeds comprises steps of: steeping of: extracting a weight ratio of the 12:1 to 20:1 roselle seeds and an ethanol solution with a concentration of 75 to 95%; and steeping the roselle seeds in the ethanol solution to obtain a suspension; and extraction of: the suspension being engaged in an extraction of a continuous and rapid oscillation with an ultrasonic energy with a total energy of 200 to 500W, wherein 1 to 3 hours of the oscillation is one cycle, and a total number of 3 to 5 cycles is lasted, in order to obtain roselle seed crude extracts.