The invention discloses a chlorella facial mask and a preparation method thereof, and belongs to the field of cosmetic preparation. The chlorella facial mask comprises a facial mask solution and facial mask paper, wherein the facial mask solution is prepared from the following raw materials in parts by weight: 60-99 parts of deionized water; 0.01 to 0.5 part of an acrylic acid (acrylate)/C10-30 alkanol acrylate cross-linked polymer, 0.01 to 0.2 part of transparent xanthan gum, 1 to 20 parts of propylene glycol, 0.1 to 10 parts of glyceryl polyether-26, 0.01 to 0.4 part of sodium hyaluronate and 0.01 to 0.4 part of hydrolyzed hyaluronic acid; according to the invention, the deep purification function of chlorella is utilized; a chlorella extract is introduced into cosmetics; entry into thedeep of the skin is realized, active ingredients are effectively released, subcutaneous fibrous tissues are activated, and collagen proliferation is promoted, so that the compactness of the collagen fibrous tissues is enhanced, the skin is easy to become soft, compact and elastic, chlorella factors entering the skin can be easily released, cells can be repaired, part of cells can be revived, and the cells can be protected.