Abstract: The alkali metal transformation during high-sodium Zhundong coal pyrolysis was investigated in a vertical tubular furnace reactor. The release characteristics, modes of occurrence of Na, the microstructure of char samples after pyrolysis at different temperatures were examined by using inductive coupled plasma equipped with atomic emission spectrometer(ICP-AES), X-ray diffractometry (XRD) and scanning electron microscopy with an energy dispersive X-ray spectrometer(SEM-EDX), respectively. Meanwhile, the release forms of alkali metal from coal were simulated by Fact sage 6.1. The results show that a part of sodium in high-sodium coal is released during pyrolysis, starting to release at 600 ℃ and reaching to 40.2% of release at 900 ℃. It is concluded that Na in the coal is released as NaCl, and no molten matter is found when the pyrolysis temperature is below 900 ℃.