The utility model belongs to the technical field of flow measurement, a testing arrangement is compared on line to the ultrasonic wave flow is disclosed for the fixed flowmeter on fluid pipeline is fixed in the test check -up, include: ultrasonic flowmeter, signal isolation unit and flow totalizer, ultrasonic flowmeter passes through the signal isolation unit with flow totalizer links to each other, when carrying out the test check -up, ultrasonic flowmeter sets up fluid pipeline is last, is located fixed flowmeter one side. The utility model provides an it compares testing arrangement on lineto promote the ultrasonic wave flow of proofreading and correct maintenance efficiency.