Considering the complex flow measurement process of traditional open channel flowmeter and the inability to accurately obtain the required flow velocity, a multi-channel open channel flow measurement system based on ARM is designed. The system combines the pitot tube principle with the differential pressure sensor, arranges the dense measuring points in the vertical line in the open channel section, converts the sensor data of each measuring point into the flow velocity during the flow measurement, and obtains the section velocity distribution curve by curve fitting, and then uses the formula. The flow rate is further calculated. The hardware system is equipped with a real-time operating system and GUI, and the parameters and curve fitting results are displayed on the LCD screen in real time, and can also be automatically uploaded to the cloud platform. The experiment results show that the system can truly reflect the flow velocity distribution of the flow measurement section, which improves the accuracy of the open channel flow measurement, and the system has a strong human-computer interaction function, which has improved flow measurement efficiency.