The invention discloses liquid shampoo and a preparation method thereof. The liquid shampoo comprises, by mass, 30-80 parts of black rice, 3-7 parts of lemon, 5-20 parts of pipal tree seeds, 3-10 parts of wild ginseng, 3-15 parts of tea seeds, 15-30 parts of saponin, 2-11 parts of platycodon grandiflorum, 2-10 parts of rhizoma anemarrhenae, 3-10 parts of polygonum multiflorum, 2-13 parts of fresh ginger, 2-18 parts of folium mori, 2-15 parts of angelica sinensis, 2-15 parts of saffron, 2-10 parts of coptis chinensis, 2-13 parts of lucid ganoderma, 2-10 parts of eclipta, 3-8 parts of medlar, 2-12 parts of astragalus membranaceus, 2-10 parts of ligusticum chuanxiong hort and 2-10 parts of aloe. The liquid shampoo is prepared according to the reasonable ratio, the effects of all the raw materials are remained, the synergistic interaction function is played through reasonable matching, and the liquid shampoo has the functions of hair cleaning, hair care, hair nourishing, hair reinforcing, hair loss preventing, hair generation, dandruff removal, itching relieving, radiation protection and dandruff generation prevention and the like.