This study introduces a particle shading tracer technique to measure flow velocity in microporous channels in industrial applications, based on the principle of utilizing tracer particles to ascertain average flow velocity. Tracer particles, typically 5 ~ 15 μm particles prevalent in industrial system fluid mediums, are employed. To enhance the relative intensity of the tracer particles′ shading signal and counteract the potential drowning effect of field electromagnetic interference, a microporous window was designed to control the laser cross-section size. The velocity of fluid medium is determined by assessing the particle′s transit time through the laser beam and analyzing its speed. The measuring device was designed and its method validated through experiments. When the Stokes number of 5~15 micron particles in the flow field is controlled below 0.1 and the flow velocity is in the range of 0.27~2.76 m/s, the deviation from the theoretical value of the measured local flow velocity in the microfluidics is less than 8%. It is proved that the method is suitable for measuring the average velocity of the flow field in the industrial system.