Patent documents refer to documents written according to the format requirements and content requirements stipulated by the patent laws of all countries in the world, which specifically record the specific technical scheme for applying for patents. As a record of scientific and technological knowledge, patent literature contains rich information resources. No matter which country's patent documents are, on the title page of the patent specification, the description items such as patent title, patent applicant, patent classification number, patent inventor, year of invention (priority time) and abstract of patent specification must be marked. Statistics on these standardized data items can reflect the output of technical activities and intellectual property protection strategies of various countries or patentees in different periods and fields. Theoretical discovery is not the object protected by patent law, so it will not be recorded in patent literature.