Abstract: Flow is one of the important parameters in industrial detection. With the development and application of the Micro Electro-Mechanical Systems (MEMS) technology, flow detection is developing towards miniaturization, high precision and intelligence. A MEMS beam-membrane structure based differential pressure flow sensor is designed, and its working principle is analyzed. The sensor is fabricated by the silicon micromachining technology, and then the airflow test and water flow test are conducted. The sensitivity by the airflow test is 0.3508mV/(ms^-1)² and the basic accuracy is 0.5885%FS. The sensitivity by the water flow test is 41.5241mV/(ms^-1)² and the basic accuracy is 0.9323%FS. The results show that the designed sensor has sufficient sensitivity and basic accuracy for the flow measurement.