Top plate two-belt height testing device and method

The invention discloses a top plate two-belt height testing device and method. The device is characterized in that a first hole sealing capsule and a second hole sealing capsule are connected through a double-acting connecting mechanism, and are compressed and reset through the telescoping of the double-acting connecting mechanism; the upper end of a test rod is connected with a rigid water pipe in the second hole sealing capsule; an oil pump is connected with an annular rodless cavity of the double-acting connecting mechanism and is used for controlling the synchronous telescopic action of two plunger top heads in the double-acting connecting mechanism; and a water pump is connected with the test rod through a water injection pipe. The method comprises of arranging equipment; connecting the first hole sealing capsule and the second hole sealing capsule through the double-acting connecting mechanism; pushing into the drill hole, and recording the pushing depth; enabling the double-acting connecting mechanism