Abstract: Ultrasonic guided wave propagation in fluid-filled cylindrical pipeline is investigated in order to put forward a new method of on-line flow measurement for calorimeter in heat-supply pipeline. The propagation speed of ultrasonic guided wave in liquid-filled pipeline is fast. In order to measure the influence of liquid flow rate on the propagation speed of ultrasonic guided wave, it is necessary to extract the propagation time of ultrasonic guided wave accurately. The application of correlation function method to calculating the propagation time of ultrasonic guided wave is introduced, and the accuracy is verified by numerical analysis and experiment. This provides a theoretical basis for applying ultrasonic guided wave to measuring the liquid flow rate in pipeline.