The utility model relates to a technical field of municipal works discloses protective structure that width can change, including roof and two curb plates, formation " pi " structure between roof and two curb plates, the roof includes the left roof and the right roof of interval arrangement, and butt -joint structural includes the connecting plate, be equipped with bolt hole row in a left side roof and the right roof respectively, the bolt hole including a plurality of looks interval arrangements is arranged to the bolt hole, and the connecting plate is equipped with a plurality of connecting holes, the connecting plate pass through the bolt respectively with left roof and right roof connection. Compared with the prior art, through left roof and right roof be equipped with bolt hole row, be equipped with a plurality of connecting holes on the connecting plate, during the installation, pass the connecting hole and the bolt hole couples together both with the bolt, because a plurality of connecting holes arrange with the bolt hole is arranged that can be connected the width of adjusting the roof with the connecting hole through the bolt hole of selecting different positions, the realization width can change to according to the next width of rationally selecting protective structure of the width of excavation slot, the suitability is very strong.