In order to explore the migration law of sulfur element and the pollutant formation in the process of coal pyrolysis，and taking Ningdong coal as the research object，X-ray photoelectron spectroscopy，13C nuclear magnetic resonance（13C-NMR)，industrial analysis and element analysis were used to analyze the internal element types，chemical valence states and bonding modes of Ningdong coal，and two types of low rank chemical structure models of Ningdong coal which contains sulfur but no ash and water content were constructed. After molecular dynamics annealing simulation and geometry structure optimization in Material Studio software，the chemical structure with obvious stereoscopic structure was obtained，which ensured that there were four sulfur atoms in the model box，to correctly summarize the sulfur migration path and productions during the coal pyrolysis process. After that，ReaxFF force field was used to simulate in 200 ps molecular dynamics at reference temperature of 2 500 K. It is found that the distribution of pyrolysis products is in good agreement with the reference simulation results，which proves the rationality of the model. Thus，the transformation characteristics of sulfur atoms in the form of mercaptan and thiophenol during initial period of coal pyrolysis was summarized. Although both types sulphur eventually migrate to tar products，there have different migration rates and stable chain structures. The migration of sulfur in the initial stage of coal pyrolysis corresponds to the reason of high sulfur content in coal tar during the actual low temperature coal pyrolysis. Increasing the simulation reference temperature or extending the calculation time is required to determine the deeper secondary reaction behavior of the sulfur migration during coal pyrolysis process.