In order to facilitate the measurement of flow velocity, flow and water depth between open channels, a portable section flow measurement system is designed. According to the requirements of the on-site environment for flow velocity and measurement water depth, a pressure sensor with a design range of 20kPa high-frequency pressure sensitive element is designed. Under the condition of a standard constant current source, the sensitivity is better than 0.25%FS; the design range is 10m/s. The err effect magneto-sensitive sensor propeller, the water flow is used to drive the propeller motion to obtain the propeller rotation speed, the startup speed is better than 0.02m/s, and the accuracy is better than 2%.Based on the ARM Cortex?-M3 core as the logic processing unit, 12 bit A/D converter, real-time storage and upload data to the management center through NB-Iot low power wide area network. The measuring device is easy to carry, light in weight.It can be operated by one person and one hand, and it can be measured in real time on site.