Abstract: A high speed on-line measuring device for coal dust concentration based on Mie scattering theory equation was designed by using Xilinx ZYNQ-7010 chip. First of all, the binary search method is used to derive the corresponding relationship between the scattered light intensity and the particle size. Then, the overall system control is established on the ARM side by the method of hardware and software cooperation, and the concentration processing algorithm is hardwareized on the FPGA side. At the same time, the light source modulation circuit and photoelectric detection circuit with the property of constant current source are optimized, and the upper computer interface is designed to communicate with the main control chip. Finally, coal dust particles with particle size less than 50 μm were selected by coal sample screen for test. The test results show that the measurement accuracy of the system is 91%, and the concentration detection and explosion warning can be realized at high speed and stably.