Through analyzing characteristics and application status of current dynamic measurement methods of coal on belt conveying, a volume measurement method of coal on belt conveying based on machine vision was proposed in view of problem of lower precision of laser belt scale. Firstly, a volume measurement model was established based on principle of trigonometric distance measurement, and a set of image acquisition device suitable for coal mine environment was used to collect images. And then fast skeleton extraction algorithm based on gradient optimization was used to get center of line laser stripe, the interpolation method based on distance threshold was adopted to repair break line. Finally, according to the volume measurement model, the volume measurement of coal was realized by calculating the center offset of the laser stripe. Test results show that volume measurement error of the method is lower than that of the common laser belt scale, which is more suitable for dynamic measurement of coal on belt conveying.