Abstract: In order to obtain quantitative information on the sulfur transformation during pyrolysis, the pyrolysis experiments of Maliantai coal from Ningxia were conducted in a lab-scale tubular reactor. The results show that 50 % to 70% sulfur of the total sulfur is fixed in the char. The desulfurization increases with the temperature and then retains about 46% when the temperature was higher than 600℃, in which the decomposition of sulfur form is dominated by the pyrite. Content of organic sulfur is higher than other sulfur forms, especially for the thiophene and sulfone. Mutual transformation of sulfur forms occurs during pyrolysis. And the desulfurization is the highest at temperature of 600℃.