Seals is an important part of the traditional Chinese paintings. The nondestructive analysis and study of seal - ink on historical paintings is useful for the identification and archaeological research. But the common test method, such as mid - infrared spectroscopy and Raman spectroscopy, are not suited to quantitative analysis and testing of big paintings, which limits their use in seal - ink research. Near - infrared ( NIR) spectroscopy combine with chemometric data evaluation, which is a developing method, potentially fulfills these requirements. 14 kinds of seal - ink with different colors and date, 5 kinds of paper and silk were collected to validate the feasibility of this method. Experiments show that this method not only can identify different kinds of seal - ink but also can evaluate the similarity between them, which may be used in dating. The appropriate subtracting treatment can remove the interfering signals of paper or silk and keep the precision of discriminant analysis.