To suppress the static time error of the ultrasonic time-difference measurement system, this paper proposes a new topology based on the auxiliary impedance matching branch, and finally a prototype ultrasonic time-difference measurement system is successfully developed based on this topology. Based on the prototype and the homemade transducer, the static time errors at different driving frequencies, different matching resistances and high-temperature operating conditions (200℃ , 230℃ and 260℃ ) were tested, and the accuracy and feasibility of the whole set of system were verified by the real-flow calibration experiments. The results show that the mean value of the system static time error and its fluctuation range can be effectively suppressed by the incorporation of the auxiliary impedance matching branch, and a minimum static time error of -0. 279 ns is realized under the high-temperature environments of 200℃ , 230℃ and 260℃ . Finally, this system achieves an accuracy level of up to 0. 15% at a low flow rate of 440 m 3 / h, and an accuracy of up to 0. 05% in the range of medium and high flow rates of 1 503 ~ 4 397 m 3 / h, which verifies the feasibility of the auxiliary impedance matching branch, and provides a high-precision and low static time difference solution for ultrasonic time difference measurement.