Speed reducer testing tool

The utility model relates to the field of speed reducers, and particularly discloses a speed reducer testing tool which comprises a supporting bottom plate. A first base and a second base are symmetrically and fixedly connected to the upper surface of the supporting bottom plate. The speed reducer body is placed in the installation groove to be fixed to complete preliminary installation, then a belt is prepared to be connected to a to-be-tested shaft of the speed reducer, then the up-down adjusting unit is controlled to move upwards to make the distance smaller than that of the belt, and the belt is conveniently installed on a belt wheel; the up-and-down adjusting unit is controlled to pull and tighten the belt downwards and then fix the belt, then the testing motor is started for testing, after testing is completed, the up-and-down adjusting unit is controlled to move upwards so that the distance can be smaller than that of the belt, the belt can be conveniently taken down from a belt wheel, and therefore th