Abstract: In order to improve the security and reliability of embedded system, a trusted root is given out, of which the core-block is OPM module. Combined with the idea of cooperative control by software and hardware, it guarantees the reliability of the whole embedded system. As stewards of the whole system security, OPM module holds the key information of the system and controls the switch of external interface and behaves of other modules such as the authentication module. At last, the rationality of the design is verified through the simulation.