Whether OEM production is illegal depends on the situation. If the OEM manufacturer obtains the permission of the trademark registrant and signs a license agreement, the OEM production is not illegal; if the OEM manufacturer does not obtain permission, it is an infringement of the exclusive rights of the registered trademark and is illegal. . Article 43 of the Trademark Law of the People's Republic of China: A trademark registrant may authorize others to use its registered trademark by signing a trademark license contract. The licensor shall supervise the quality of the goods used by the licensee using its registered trademark. The licensee shall ensure the quality of the goods using the registered trademark. If the registered trademark of another person is used with permission, the name of the licensee and the place of origin of the goods must be marked on the goods using the registered trademark. If the licensor permits others to use its registered trademark, the licensor shall submit its trademark use license to the Trademark Office for record, and the Trademark Office shall announce it. The trademark use license shall not be used against bona fide third parties without registration. Article 57 of the "Regulations on Procedures for Handling Road Traffic Accidents" commits any of the following acts, which shall constitute an infringement of the exclusive right to use a registered trademark: (1) Using the same trademark on the same product without the permission of the trademark registrant trademark; (3) Selling goods that infringe the exclusive rights of registered trademarks.