Legal analysis: Invention patents must be subject to substantive examination. Within three years from the filing date of an invention patent application, the patent administration department of the State Council may conduct a substantive examination of the application upon request made by the applicant at any time.
Legal basis: "Patent Law of the People's Republic of China" Article 35 Within three years from the filing date of an invention patent application, the patent administration department of the State Council may, upon request submitted by the applicant at any time, The application shall be subject to substantive examination; if the applicant fails to request substantive examination within the time limit without justifiable reasons, the application shall be deemed to have been withdrawn. When the patent administration department of the State Council deems it necessary, it may conduct a substantive examination of an invention patent application on its own.