Parallelism measuring device

The utility model belongs to the technical field of parallelism measurement, and discloses a parallelism measuring device, which is used for measuring the parallelism between a first component and a second component which are arranged at an interval and comprises a mounting base body, a reference piece and a measuring piece, and the reference piece is connected to the mounting base body and is attached to the first component; the measuring piece is movably connected to the side, back on to the reference piece, of the mounting base body and can be attached to the second component, and the parallelism between the first component and the second component is obtained according to the inclination of the measuring piece relative to the reference piece. When the parallelism measuring device is applied to the water heater, the first part and the second part are equivalent to two supporting frames on the water heater, and the measuring device can conveniently, accurately and quickly measure whether the parallelism bet