The time limit for substantive examination of an invention patent is three years from the date of filing the patent. \r\nArticle 35 of the "Patent Law" stipulates: Within three years from the date of application for an invention patent, the patent administration department of the State Council may review the application based on the request made by the applicant at any time; if the applicant does not have justifiable reasons, If substantive examination is not requested within the time limit, the application will be deemed to have been withdrawn. \r\nFor more information about the substantive examination period for invention patents, please enter: /ask/32a61f1615826071.html?zd to view more content