To achieve online automatic measurement of the mass flow rate of granular materials in the chute, according to the difference in dielectric properties between granular materials and air, a chute mass flow meter for granular materials based on the capacitance method is designed. The device uses STM32 microcontroller, the capacitance-to-digital Converter chip AD7746 and the plate conversion circuit with MT8816 as core chip of the to build a data acquisition system to achieves effective acquisition of the of eight-plate rotary excitation sensors. A mass flow test bench was built, maize, wheat and pellet compound feed as test materials，the relationship between mass flow rate and capacitance output variation was calibrated, and the mass flow prediction models of three kinds of granular materials were constructed. The model coefficient of determination R2 is 0.990 4, 0.993 9 and 0.987 9 respectively. The chute mass flow meter for granular materials performs well when the chute inclination angles of 15°, 25°, 35°, 45°,55°，the maize and wheat mass is 30, 50 and 70 kg，the pellet compound feed mass is 30，50，65 kg . Regarding measurement accuracy, the average relative errors of maize, wheat and pellet compound feed were measured 3.11%, 3.76% and 3.55% respectively. The results show that it is feasible to apply the capacitance method to the online measurement of mass flow rate during the transport of detect the mass flow of granular materials in the chute, and can achieve the online automatic measurement of mass flow rate of measuring granular materials.