The invention discloses pure plant enzyme liquid shampoo containing tea bran and used for hair nourishing and protection and hair growth promotion and a preparation method thereof. The liquid shampoo is prepared from, by weight, 5-10 parts of tea bran, 3-5 parts of ginger, 6-10 parts of white mulberry root-bark, 3-5 parts of walnut kernel, 3-5 parts of grapefruit kernels, 3-5 parts of Chinese torreya, 3-5 parts of cacumen biotae, 3-5 parts of eclipta alba, 1-4 parts of gallnuts, 3-5 parts of groundsel, 1-3 parts of dandelion, 1-2 parts of Chinese honeylocust spines, 1-2 parts of soapberries, 1-2 parts of fleece-flower roots and 1-3 parts of lactic acid bacteria. The liquid shampoo is safe, non-toxic, mild and non-irritant, is a pure natural plant liquid shampoo and has the effects of hair nourishing and protection, hair growth promotion, scalp nourishing and regulation, dandruff removal, itching relieving, oil removal, disinfection, hair loss prevention, avoidance of hair dryness, withering, yellowing, splitting, breakage and dropping, white hair prevention and damaged hair repair.