This paper designs the electromagnetic flowmeter in partially filled pipes (EMF-PF), which sensor sets four electrodes. One pair of the electrodes is set on the pipe bottom as the signal injection electrodes that inject the AC pulses used to determine liquid fill height. One pair of long-arc electrodes is set on the pipe wall as the measurement electrodes. The measurement electrodes alternate duties, sensing both the flow and fill height signals. Both the flow and fill height raw signals are disposed in different time period by the same signal processing channels. Experiment result shows that the designed EMF-PF can achieve the flow measurement in partially filled pipes, and the measurement accuracy of this EMF-PF meets the actual requirements.