Legal analysis: The statute of limitations for infringement of patent rights is two years, starting from the date when the patentee or interested party learns or should have learned of the infringement. If an invention patent application is published but before the patent right is granted, appropriate royalties are not paid for use of the invention, the statute of limitations for the patentee to demand payment of royalties is two years from the date when the patentee learned or should have learned that others were using his invention. However, if the patentee has known or should have known about it before the date of grant of patent right, the calculation shall start from the date of grant of patent right.
Legal basis: "Patent Law of the People's Republic of China" Article 68 The statute of limitations for infringement of patent rights is two years. calculated from the date of the infringement.