The methods of accurate measurement on the real-time solid mass flow rate are very limited, especially for non intrusive measuring approaches. This paper presents a non-intrusive measurement system on solid mass flow rate. The measuring principle is based on microwave attenuation theory and microwave Doppler Effect. A series of experiments have been carried out to test the microwave measurement method. The effects of particle properties in terms of size and relative permittivity on the measuring results have been carefully discussed. The correlations between the output signal and the solid mass flow rate have been investigated. The experiment results show that the size and material of the measured solids can significantly influence the reflected microwave signal. To improve the measurement accuracy, the correlation related on the functions of particle diameter and permittivity is proposed for the solid mass flow rate. Furthermore, the experiments under the unsteady flow condition confirm that this method is promising to be applied in the actual industrial processes. (C) 2017 Elsevier B.V. All rights reserved.