The invention relates to an energy consumption management method for a fixed-priority IO device. The method comprises the steps of scheduling tasks by utilizing a rate-monotonic double-priority policy; calculating estimated idle time ST(Ti,j,t) from task instances Ti,j; calculating idle time LT(Ti,j,t) meeting a conditional time point recently and coming from the task instances Ti,j; calculating device idle time DS(lambda k,t) of a device lambda k; when the device lambda k is in an active state and the device idle time DS(lambda k, t) is longer than device critical time B(lambda k), switching the device lambda k to be in a sleep state, and setting activation time Up(lambda k) of the device; and when the device is in the sleep state and the current time is equal to the active time Up(lambda k) of the device, switching the device to be in the active state. According to the method, the execution of resource-constrained periodic tasks can be finished in a deadline, and resources can be used in a mutual exclusion manner; and the energy consumption of the device is reduced, so that the production cost of products is reduced and the replacement cycle of batteries is shortened. By implementing the method, the energy can be saved by about 33.28% in comparison with the prior art.