Adding suitable Na2O to lime sintering method can improve the alumina leaching ratio effectively, and reduce the sintering temperature. Meanwhile, the formation of β-2CaO·SiO2 will lead to the “secondary reaction”. The effect of sintering temperature and holding time on the stability of β-2CaO·SiO2 were studied by simulated dissolution experiments and XRD. The results shows that the decompositions ratio of β-2CaO·SiO2 rised with the sintering temperature rising. Therefore, the stability reduced continuously. The decomposition ratio of β-2CaO·SiO2 was 13.98% when the sintering temperature was 1350℃, but it increased to 16.54% when the sintering temperature was up to 1450℃. The decomposition ratio of β-2CaO·SiO2 increased firstly and then decreased with different holding time. When the holding time was 30min, the decompositions ratio of β-2CaO·SiO2 was 7.04%. But it increased to 7.96% when the holding time was extended to 60min.