In order to reveal the effects of coverage and arrangement of ultrasonic track on the measurement accuracyof transit- time ultrasonic flowmeter,the characteristics of the 2D ultrasonic track model of 3D ultrasonic track wereanalyzed,and some formulas were deduced to calculate the coverage area in different covering modes,the numberof track segments as well as the distance between the centerlines of track segments and the center of pipe crosssec-tion,respectively.Moreover,a parameter design of the 2D ultrasonic track model was conducted.The results ofcase study indicate that the calculation method of the 2D ultrasonic track model of 3D ultrasonic track is effective.