How long is the statute of limitations for patent infringement?

According to Article 74 of the Patent Law, the limitation of action for patent infringement is three years, counting from the date when the patentee or interested party knows or should know about the infringement and infringer.

If the patentee fails to pay an appropriate royalty before the patent right is granted after the publication of the application for a patent for invention, the limitation period for requesting the royalty is three years, counting from the date when the patentee knows or should know that others are using his invention. However, if the patentee knows or should know before the patent right is granted, it shall be counted from the date when the patent right is granted.