The study adopting the improved soda lime sintering process was focused on the process of aluminum dissolution, with the desilication oil shale ash used as the raw material. This paper mainly deals with the influence of sintering temperature, sintering time, alkali aluminum ratio and calcium silicon ratio on the phase characteristics and the aluminum dissolution rate. The results show that the alumina extraction rate could be up to above 94% under the conditions of sintering temperature 1 150℃, sintering time 1.5 h, and ratio of raw feed rate Na₂O/Al₂O₃=1.0, CaO/SiO₂=1.0.