A purity certified reference material for Basic Orange II was studied by means of raw material purification, qualitative analysis，quantitative analysis，homogeneity test，stability test，as well as characterization and uncertainty evaluation. The candidate standard substance was prepared by recrystallization of purchased Basic Orange II. The candidates were purified，dried，and then encapsulated in brown glass bottles. The homogeneity and stability of several sample bottles were studied by stratified random sampling. The chemical composition of the candidate reference material of Basic Orange II was confirmed by infrared（IR） spectrum，high resolution mass spectrometry （MS） and proton nuclear magnetic resonance（NMR）. 7 qualified laboratories were cooperated for certification of Basic Orange II. The purity of the product was analyzed by mass balance method （concluding area normalization, water content, ash content and residual solvent analysis by liquid chromatography）. The results showed that the certified value of the purity reference material was 99.2% and the relative expansion uncertainty was 1.0%（k = 2）. The purity reference material was identified as the national grade II certified reference materials，which was numbered GBW（E）100372，and was expected to be used in the calibration of instruments and method evaluation in food and cosmetic analysis.