The occurrence and geological genesis of pyrites in Late Paleozoic coals of North China have been systematically studied in terms of coal petrology, coal chemistry, elemental geochemistry and sulfur isotope geochemistry. The results suggest that eight types of pyrite, i.e., framboidal, automorphic granular, oolitic, massive, homogeneous spherical, allotriomorphic, nodular, joint| and fissure|filling pyrites can be subdivided under the microscope. Four generations of pyrite are also recognized according to the shape, size, coexisting assemblage, spacial distribution relationship with macerals, the contents of sulfur and iron, atomic S/Fe ratios and associated elements in pyrites. Sulfur in Late Paleozoic coals of North China is of diverse source as evidenced by sulfur isotope variations in the pyrites. The δ{}+{34}S values of pyrite generated at the early stage tend to be negative, and at the late stage, positive. The occurrence and geological genesis of pyrites in Late Paleozoic coals of North China have been systematically studied in terms of coal petrology, coal chemistry, elemental geochemistry and sulfur isotope geochemistry. The results suggest that eight types of pyrite, ie, framboidal, automorphic granular, oolitic, massive, homogeneous spherical, allotriomorphic, nodular, joint | and fissure | filling pyrites can be subdivided under the microscope. Four generations of pyrite are also recognized according to the shape, size, coexisting assemblage, spacial distribution relationship with macerals, the contents of sulfur and iron, atomic S / Fe ratios and associated elements in pyrites. Sulfur in Late Paleozoic coals of North China is diverse source as evidenced by sulfur isotope variations in the pyrites. The δ {} + {34 } S values ​​of pyrite generated at the early stage tend to be negative, and at the late stage, positive.