From the perspective of resources, the think tanks are large knowledge base with rich knowledge resources. In the era of knowledge-driven economy, the knowledge resources management and measurement focus more on knowledge level than the carrier level. Knowledge elements are the key role when dealing with knowledge itself. Research on the classification, mining and index of Chinese text provides the technological support for knowledge element extraction of Chinese think-tank products. The descriptive rules, induced from the classification of extracted knowledge elements, would benefit the management and assessment of Chinese think-tank products from level of knowledge. According to the method of building thesaurus for text extraction, the paper chooses the accessible think-tank research products from China Institute of International Studies in 2015 as samples. The types and descriptive rules of Chinese think-tank products are summarized after man-made selection and purification of extraction results. Five kinds of knowledge elements such as fact knowledge element, definition knowledge element, conclusion knowledge element, method knowledge element and relation knowledge element as well as 16 types of descriptive rules of Chinese think-tank products are summed up.