legal ground
Article 35 of the Patent Law of People's Republic of China (PRC)
Within three years from the date of filing, the patent administration department of the State Council may conduct substantive examination according to the request made by the applicant at any time; If the applicant fails to request substantive examination within the time limit without justifiable reasons, the application shall be deemed to have been withdrawn.
Article 36
When requesting substantive examination, the applicant for a patent for invention shall submit reference materials related to his invention before the filing date.
Where an application for a patent for invention is filed in a foreign country, the patent administration department of the State Council may require the applicant to submit the information retrieved during the examination of his application in that country or the information on the examination results within a specified time limit; If the application is not submitted within the time limit without justifiable reasons, the application shall be deemed to have been withdrawn.
Article 32
The applicant may withdraw his patent application at any time before being granted the patent right.