Spray dust mechanism is to use spray to wet and reduce the coal mine dust. Based on lattice Boltzmann method, the dynamic behaviors of droplet spreading on solid surface are simulated numerically in consideration of the molecules reaction between fluid and solid. Results show that the spreading diameter and dynamic contact angle change exponentially with time. The relationship between droplet surface tension and maximum spreading diameter is determined; it is shown that the wettability of solid surface has a great influence on the maximum spreading velocity. All the above numerical results are in good agreement with the experimental and theoretical results reported in the literature. Moreover, the solid surface with high hydrophobicity is further investigated. It is found that the spreading contact angle can be less than 90° if the droplet surface tension is small enough, which agrees well with the theoretical formula. The simulation also shows that there occurs oscillations in the spreading process and retraction when the droplet spreads to its maximum.