Substantive examination refers to the examination made by the State Patent Office on the novelty, inventiveness, practicality and other substantive contents of the invention for which a patent is applied.
 Within three years from the date of application for a patent for invention, the State Patent Office may, at the request of the applicant at any time, examine the application in substance;
 If the applicant does not request substantive examination within the time limit without justified reasons, the application shall be deemed to have been withdrawn. When the State Patent Office deems it necessary, it may, on its own, examine the application for a patent for invention in substance.
 For the substantive examination that has been applied for, some can take the form of written examination, that is, through the statement of the application materials to understand the relevant situation and conduct examination, but some substantive examination still needs to conduct on-site verification to confirm the true situation.
 [Legal Basis]
 Article 35 of the Patent Law states that within three years from the date of filing an application for a patent for invention, the patent administration department under the State Council may, at the request of the applicant at any time, examine the application in substance; If the applicant does not request substantive examination within the time limit without justified reasons, the application shall be deemed to have been withdrawn.
 When the administrative department for patent under the State Council deems it necessary, it may, on its own, examine the application for a patent for invention in substance.