Liquid pipeline systems are widely used in liquid transportation systems such as water-supply and drainage systems, water cooling systems, and oil pipeline systems. Liquid flow rate measurement in a pipeline system is very important for effective repair and maintenance, high-efficiency operation and pipeline safety. In this paper, a liquid flow rate measurement method suitable for a liquid pipeline is proposed, in which an acoustic emission (AE) sensor is applied to the surface of the pipeline. We constructed a flow rate measurement system consisting of an AE sensor and a signal processing circuit for transforming AE signals generated by the liquid pipeline flow into a corresponding flow rate. The characteristics of the flow rate measurement system were experimentally determined, using tap water as the liquid. The results demonstrate the possibility that a steady flow rate can be measured with a repeatability of approximately 7% over regions in which the flow rate ranges from 4.0l/min to 11.0l/min in a pipeline with a diameter of 13.3mm or 0.5l/min to 4.0l/min in a pipeline with a diameter of 6.2mm. The scope of application of the proposed measurement system is discussed.