The physicochemical properties of coal dust significantly affect its toxicity and dust suppression efficiency. Currently, lab-crushed coal dust is commonly used for characterization instead of the original coal dust (OCD) sampled from underground mining sites. This practice leads to an inaccurate understanding of the underground coal dust properties. To address this issue, the study directly collected 18 OCD samples from various underground mining sites and characterized their physicochemical properties, and the variation of these physicochemical parameters of OCD with various coal rank were analyzed. The results show: OCD has a small particle size (average 26.49 μm), and around 21% of particles are under 10 μm. OCD has a well-developed pore structure, with an average total pore volume of 8.24 × 10