The Single-meter water meter test bench may be divided into two kinds: Testing type and producing type. For testing-type there is a straight tube whose length is 15 times diameter in the front and at the back of water meter position separately, Such devices are suitable for calibration and full-performance test of water meters in running-water company and water meter testing station. The producing type economical and practical which is suitable for water meter manufacturers. For diameter over 80mm the devices are equipped with changing-over unit, electrical controller, electric flow regulator and two-position four-way solenoid. All operation adopts hydraulic or pneumatic control by buttons. Moreover, a rectifier and a straight tube are equipped to ensure accurate test result, the length of tube are 10 times diameter at the front of meter and 5 times at the back. To relieve user's expense the worktable of large-diameter devices can be made from ordinary steel instead of stainless steel. And the working measure, meter clamp and changing-over unit are still made form stainless steel.