The invention provides a black rice anthocyanin extracting method. The black rice anthocyanin extracting method specifically comprises the following steps: taking a black rice grain as a material, preprocessing the black rice grain, coarsely extracting the anthocyanin in the black rice grain, and then sequentially perform ultrafiltration, nanofiltration, macroporous resin adsorption, ethyl alcohol elution, secondary nanofiltration, and freeze-drying in vacuum to obtain a freeze-dried powder of the black rice anthocyanin. The black rice anthocyanin extracting method provided by the invention is good in selectivity; impurities of polysaccharide, organic acids, proteins and the like in the black rice anthocyanin can be effectively separated; the extracting rate is high, the product quality is high, even trace of the black rice anthocyanin is also extracted, the extracting speed is high, the operation is simple, and the discharge of effluent is low.