The utility model relates to a two-dimensional mechanical arm self-leveling device of a test water tank, which comprises the test water tank, the test water tank is a box body structure enclosed by a bottom plate, a
front panel, a left panel, a rear panel and a right panel, a horizontal straight arm is arranged above the
front panel of the test water tank, and the horizontal straight arm is used for installing a two-dimensional mechanical arm. The right side of the horizontal straight arm is connected with a horizontal
side arm, sensor supports are arranged at the two ends of the side face, facing the inner cavity of the test water tank, of the horizontal straight arm and the side face, facing the inner cavity of the test water tank, of the horizontal
side arm, and distance measuring sensors are installed on the sensor supports; a first levelness adjusting device is installed between the upper end of the left panel and the bottom of the horizontal straight arm, and a second levelness adjusting device is installed between the upper end of the right panel and the bottom of the horizontal
side arm. The device is simple to operate and high in accuracy, the distance between the horizontal straight arm and the water surface and the distance between the horizontal side arm and the water surface are measured through the distance measuring sensor, the position is electrically adjusted, and the adjusting precision is improved; the positioning is convenient, and the positioning efficiency is improved.