Transmission upper cover airtightness checking tool

The utility model relates to a transmission upper cover airtightness checking tool. The transmission upper cover airtightness checking tool comprises an upper cover body. The transmission upper cover airtightness checking tool comprises a sealing plug, a bottom plate, a first sealing pad, a cover plate, a second sealing pad, a first rubber gasket and a fastening bolt; the sealing plug is fixed in a hole on a first wall surface of the upper cover body; a lower end of the upper cover body, which is provided with an opening, is supported on the bottom plate; the first sealing pad is clamped between the upper cover body and the bottom plate; the upper cover body is tightly fixed with the bottom plate through bolts; the cover plate is fixed at an opening at a top portion of the upper cover body; the second sealing pad is arranged between the cover plate and the opening at the top portion of the upper cover body; the first rubber gasket is sleeved on the fastening bolt; the fastening bolt is connected with a throug