Abstract: In order to obtain the influences of different reaction atmospheres on transformation and deposition characteristics of sodium in Zhundong high sodium coal for circulating fluidized bed technology, gasification (reducing atmosphere) and combustion (oxidizing atmosphere) experiments were carried out, respectively, at 950℃ for Xinjiang SEH high sodium coal in a 0.4 t/d circulating fluidized bed experimental apparatus. The results show that Na in fly ash and deposition ash exists mainly as NaCl. Na and Cl are easier to be reserved in bottom ash and fly ash during gasification comparing with combustion, and correspondingly less Na and Cl enter into gas phase. Part of NaCl is sulfurized by SO₂ and more stable Na₂SO₄ is produced under combustion atmosphere and condenses on the surface of ash deposition probes. More fine particulates are produced during combustion and perform worse deposition problems. The corrosion of HCl to the metal wall exists in the process of SEH coals' combustion and gasification.