The invention provides an arrangement method for the protective group of a chain repetitive-use section. The chain repetitive-use section comprises a plurality of synchronous number system devices which can make up a long chain, and a protective link exists between every two of the synchronous number system devices, being called a section. The arrangement method is characterized in that the devices at the two sides of an odd section are incorporated into one protective group, in which protective relations are arranged for the links on the sections of the devices; also the devices at the two side of an even section are incorporated into another protective group, in which the protective relations are arranged for the links on the sections of the devices. As arranging the protective groups of the chain repetitive-use section, the method of the invention saves the ID resource of the protective group, and the operation is convenient and time-saving.