Dynamic behaviors of gaseous sulfur-containing compounds evolved from pyrolysis of six Chinese coals were studied in the temperature range of up to 800 degrees C under N-2 and H-2. The released amount of total sulfur-containing gases was traced by all online flame photometric detector (FPD). Simultaneously, the changes of different sulfur forms, including H2S, SO2, COS and CS2, also were investigated using an online mass spectrometer (MS). FPD results show that the effect of H-2 on gaseous sulfur evolved is complex, which promoted certain peak and suppresses other peaks. Based on the data from MS, it is suggested that a series of competitive reactions between active sulfur and other active matters during pyrolysis may impact oil the sulfur form in gas phase. Interactions between active sulfur-containing intermediates and the coal matrix are attributed to be the main factor determining the dynamic behavior.