Abstract: Objecttives The influence of moisture in raw coal, particle size and coal bunker material on the fluidity of raw coal was studied to find out the main reasons for coal clogging in raw coal bunkers. Methods A raw coal flowability experimental device was designed and built to conduct flowability experiments on raw coal with different moisture and particle sizes, and flow characteristics diagrams were drew to obtain the effects of various factors on raw coal flowability. Results The greater the moisture in the raw coal, the more right the broken line in the flow characteristic diagram is, the less the falling mass, the worse the mobility,and the greater the rotation angle required for complete falling. The difference in the initial position of coal falling is due to the difference in static friction between different particle sizes, resulting in different repose angles. At the same time, the decrease in moisture will reduce the friction force and increase the falling mass. The liquidity bend line of polytetrafluoroethylene material is located at the front, and the friction coefficient at the bottom is small. At the same angle, the mass drops more and the mobility is enhanced.Conclusions Moisture plays a key role in the fluidity of raw coal, the influence of particle size on the fluidity of raw coal is weak, and only the interaction with moisture can have a great influence on the fluidity of raw coal. Material also has a greater impact on the fluidity of raw coal, but when the moisture is low, the impact can be ignored.