The invention provides a dismounting and mounting method capable of completely dismounting an expansion bolt. The problem that expansion bolts cannot be dismounted after being assembled is solved. The expansion bolt comprises a screw. A fastening threaded rod is arranged at the small end of the screw. A conical-table dovetail column is arranged at the big end of the screw. An expansion threaded section is arranged on a rod body. An inner sleeve is connected with the periphery of the screw in a sleeving mode. A plurality of inner tail grooves which divide the tail end of the inner sleeve into a plurality of inner expansion strips are formed in the tail end of the inner sleeve. An assembly threaded section is arranged on the inner circumferential wall of the inner sleeve. The assembly threaded section is in threaded fit with the expansion threaded section. A plurality of inner pulling holes are formed in the head end of the inner sleeve. An outer sleeve is connected with the periphery of the inner sleeve in a sleeving mode. A plurality of outer tail grooves which divide the tail end of the outer sleeve into a plurality of outer expansion strips are formed in the tail end of the outer sleeve. A plurality of outer pulling holes are formed in the head end of the outer sleeve. The expansion bolt further comprises a fastening cover. The fastening cover is connected with the head end of the outer sleeve, the head end of the inner sleeve and the head end of the screw in a sleeve mode. The fastening threaded rod of the screw is sleeved with a nut in a connected mode. The expansion bolt can be completely dismounted, so that the restoration completeness is improved and the restoration service life is prolonged.