The invention discloses a selenium sulfide anti-dandruff hair conditioner and a preparation method thereof, and belongs to the field of hair conditioners. The selenium sulfide anti-dandruff hair conditioner and the preparation method thereof aim at solving the technical problems that an existing selenium sulfide lotion is strong in irritation and likely to make hair dry and rough and difficult to comb after being used. The selenium sulfide anti-dandruff hair conditioner is prepared from selenium sulfide composite ultra-fine powder, wool fat, cetanol, octadecanol, vaseline, chitosan, 10% formic acid, 0.5%-1.0% of N,N-dimethylododecylamine oxide, soluble essence and deionized water, wherein the particle size of the selenium sulfide composite ultra-fine powder ranges from 1 micrometer to 50 micrometers. The method includes the steps that firstly, an oil phase and a water phase are prepared; secondly, the oil phase and the water phase are subjected to homogeneous emulsification; thirdly, the selenium sulfide composite ultra-fine powder is added and continuously stirred for 20 min, and then the selenium sulfide anti-dandruff hair conditioner is obtained. The product is weak in irritation, uniform in dispersity and stable in performance and makes hair easy to comb, silky and glossy.