Abstract: Based on the fact that the formation of sodium aluminium hydrosilicates can be avoided on the experimental condition of high liquid-to-solid ratio (20:1), the secondary reaction process is divided into two sections according to the characteristics of dynamic process during clinker-leaching. One of the two processes, namely, the process of SiO₂ dissolving into sodium aluminate solution was detailedly researched. Through processing all data with a fitting kinetic model, the corresponding kinetic equation was deduced. The results demonstrate that the process has an apparent activation energy of 24.86 kJ· mol^-1, which serves as an indication that corresponding reactions of this process can easily happen. Since the effect of Al₂O₃ mass concentration in sodium aluminate solution is more than those of Na₂CO₃ mass concentration and NaOH mass concentration greatly, it can be considered that the reaction between calcium silicate in clinker and NaAl(OH)₄ is the main reason to result in SiO₂ entering into sodium aluminate solution.