Abstract: A reference material for composition analysis of selenium in water was developed by using the gravimetric-volumetric method on the basis of determination of the high-purity selenium and with high-purity selenium, high-purity hydrochloric acid, and triple purified water as raw materials. The homogeneity and stability of the developed reference material were examined by using the F test and the linear fitting method, respectively. The results showed that the reference material has good homogeneity and short-term and long-term stability, with the standard value of 1000 μg/mL and the relative expanded uncertainty of 1% (k=2). The ICP-OES method was used to compare the reference material with another domestic reference material, demonstrating the accuracy and traceability of the value of the reference material.