The invention provides a protection method and device for a serial bus communication network, which can be applied to a master site in a serial bus communication network topology structure. The network topology structure comprises a master site and a plurality of slave sites, wherein the master site is connected to each slave site in series to form a loop structure; each slave site is in a working mode for reception and unvarnished transmission of data; the method comprises a step that the master site changes a data sending port to form a new work data loop with a device node which is affected by a fault when receiving a fault report about the fault of the loop structure. The invention also provides a protection device adopting the method. In comparison with the existing protection device, a large amount of invalid data and repeated data in the loop can be avoided, the data processing amount of each device in the loop structure is reduced, the protection effect is optimized and the overall power consumption of the loop is reduced.