The utility model discloses a protection device for glass substrate limit portion detects and uses camera camera lens, this protector includes the protection casing, the protection casing forms to the open cardinal principle drum structure of one end, the open pot head of protection casing is established on camera lens (7) of camera (8), light trap (4) have been seted up to the blind end of protection casing, be provided with intake pipe joint (9) on the lateral wall of protection casing, be provided with air pressure adjusting valve (3) on this intake pipe joint (9), through to filling in the protection casing into gaseous, make the atmospheric pressure in the protection casing be greater than external atmospheric pressure, thereby avoid external water, steam, impurity such as dust get into the protection casing and adsorb the surface at the camera lens, the service life of the camera lens is effectively prolonged, the influence of external factor to shooing has been reduced, be favorable to the continuous of production.