The invention discloses an interface protection method and device for a vehicle-mounted machine. The method comprises the following steps of determining a calling path corresponding to an interface and each calling node contained in the calling path; monitoring the calling nodes contained in the calling path, generating the monitoring result data containing the calling records of all calling nodes; when a calling instruction generated for the interface is monitored, determining whether the calling record of each calling node contained in the monitoring result data is matched with the calling path corresponding to the interface; if not, intercepting the calling instruction. According to the scheme provided by the invention, the interface of the vehicle-mounted machine is monitored by the IDR tools in the automobile guardian client, so that the illegal calling behaviors can be found and blocked in time so as to guarantee that the interface is not called by illegal programs.