The invention relates to anti-dandruff shampoo and a preparation method thereof. The anti-dandruff shampoo is prepared from a cationic polymer, zinc pyrithione, nonionic emulsifying wax, silicon oil, a surfactant and deionized water. The nonionic emulsifying wax and zinc pyrithione are mixed and sheared in water, nonionic emulsifying wax emulsion droplets wrapped with the zinc pyrithione are formed and suspended in liquid, so that the shampoo provided by the invention hardly produces precipitates, and stability is improved; meanwhile, on the basis, the cationic polymer adopts polyquaternary ammonium salt-10, tea leaves and an orange peel composition, the composition can be effectively combined with hairs by virtue of a specific treatment method, and antioxidant and antibacterial effects of the composition are enhanced; and multiple tests explore and determine ratio of other components, so that the shampoo provided by the invention not only has good cleaning effect but also has obvious stability.