The invention discloses a method for preparing 2-chloro-4-methylpyridine-3-carbonitrile. The method comprises the following steps: at -20 DEG C to 50 DEG C, a hydrogen chloride solution is used for treating raw materials containing 4,4-dicyano-3-methyl-3-butenal dimethyl acetal. 2-chloro-4-methylpyridine-3-carbonitrile whose HPLC purity reaches 99% or above can be conveniently obtained, which has important meanings for subsequent preparation of high purity 2-chloro-4-methylpyridine-3-carbonitrile and nevirapine; the method has the advantages of short process route, simple operation, high yield, low cost, etc., a highly toxic product phosphorous oxychloride is avoided, discharge of waste water is reduced, and the method is very suitable for industrial production.