Waste gas collecting cover and collecting method thereof

The invention discloses a waste gas collecting cover and a collecting method thereof. A cover body is fixedly connected with a telescopic pipe and located below the telescopic pipe, an exhaust pipe isfixedly connected with the telescopic pipe and located above the telescopic pipe, a positioning frame is fixedly connected with the exhaust pipe and located on the right side of the exhaust pipe, a sliding rod is fixedly connected with the cover body and located above the cover body and on the right side of the telescopic pipe, and a bayonet lock is detachably connected with the sliding rod and located above the positioning frame. The cover body is connected with the exhaust pipe through the telescopic pipe in a screwed mode, an adjusting device can adjust the elongation of the telescopic pipe according to the specifications of production equipment so as to change the height of the cover body, waste gas collecting covers of other models do not need to be replaced, the problem that the waste gas collecting covers