The invention discloses a rose-lily plant beverage and a preparation method thereof. Each 1000 mL of the beverage comprises the following components by weight: 1.0 to 5.0 grams of rose extract, 0.2 to 1.0 gram of lily extract, 1.0 to 10 grams of red date concentrate, 1.0 to 5.0 grams of chrysanthemum morifolium concentrate, 1.0 to 15 grams of longan concentrate, 0.01 to 0.2 gram of stevioside, 30 to 80 grams of white granulated sugar, 0.75 gram of critic acid, 0.3 gram of potassium citrate, 0.225 gram of sodium citrate, and the balance being water. The beverage has the advantages that the formula is reasonable; the beverage does not contain any essence, pigment, or antiseptic; stevioside is taken as the sweetener and is beneficial for the health; rose, lily, red date, chrysanthemum morifolium, and longan are compounded to generate the functions of clearing heat, purging fire, nourishing yin, moistening the lung, maintaining beauty, and keeping young; the color is natural, the beverage is transparent and clear, the taste is fresh, and the beverage is suitable for the young and the old.