Abstract: The rates of sulfur fixing and loss on ignition of 4 main mining coal seams aged in Permo-Carboniferous in Hancheng mining area,Shaanxi are analyzed.The sulfur of 96% in Seam No.11,98% in Seam No.5,92% in Seam No.3,94% in Seam No.2 is decomposed and lost in ignition process under 800~850℃ for 2h.The remained sulfur in cider occurred generally in sulfur form.The fixing rate is closely related to ash content,especially the CaO in coal ash.The loss on ignition of sulfur in raw coal is related to contents of total sulfur,organic and inorganic sulfur.