The invention discloses an adjustable electricity meter fixing device and a use method thereof. The adjustable electricity meter fixing device comprises a first fixing plate, a second fixing plate and an installing plate. Two positioning plates are connected between the first fixing plate and the second fixing plate. The internal side parts of the two positioning plates are provided with lug plates. The first fixing plate is provided with a first slide rail. A first slide block and a second slide block are slidably matched on the first slide rail. The second fixing plate is provided with a second slide rail. A third slide block and a fourth slide block are slidably matched on the second slide rail. A first connecting rod is connected between the first slide block and the third slide block. A second connecting rod is connected between the second slide block and the fourth slide block. The installing plate is fixed on the first connecting rod and the second connecting rod. The installing plate is provided with two clamp slots which are matched with hooks arranged at the rear side part of an electricity meter. The adjustable electricity meter fixing device is convenient to install and detach, low in cost, high in the overall structural strength, firm in installation, wide in range of application and long in the service life and can perform appropriate height adjustment according to the requirements so that the adjustable electricity meter fixing device has the effects of safety and reliability.