Due to its high silicon and aluminum content， low silicon and aluminum ratio, fly ash is often used to synthesize low silicon pure phase sodalite. In order to improve the high-value utilization of fly ash, sodalite was synthesized from fly ash using solvent-free method. The effects of ash-alkali ratio, crystallization time and crystallization temperature on sodalite phase formation, microstructure and crystallinity were studied. The results show that crystaline pristine sodalite is prepared from fly ash with ash-alkali ratio of 1∶0.8 (mass ratio), crystallization time of 16 h and crystallization temperature of 160 ℃. The ash-alkali ratio has a significant effect on relative crystallinity. The synthesized sodalite has microporous and mesoporous composite pore structure. The N2 adsorption-desorption isotherm of sodalite isotherm reveals a typical IV isotherm with a type III hysteresis loop. Sodalite has high aluminum content， and has good thermal stability. Compared with the hydrothermal method for synthesizing sodalite, this experimental method utilizes fly ash with high efficiency， and provides a new way for the utilization of fly ash.