A protective cover including venting and fastening structures. The venting structure includes at least one vent located on the protective cover at a predetermined position, a hood loosely shielding the vent, and an outward opened V-sectioned bag located between the vent and the hood and having through holes spaced near an upper front edge to communicate with the vent, allowing residual heat and moisture to escape from the protective cover via the vent while external rainwater is stopped by the V-sectioned bag from invading the protective cover via the vent. The fastening structure includes a plurality of fixing hooks, each of which includes a plate for connecting to the protective cover via a tie-down loop and a hook provided on the plate for hooking to the vehicle or a hauler thereof, so that the protective cover is firmly tied to the vehicle or the trailer.