Aiming at a new type of roasted titanium slag which is prepared with a new process proposed by Institute of Process Engineering, the process of leaching roasting titaniferous slag with hydrochloric acid under pressure was using to solve the problem of low sulfuric acid decomposition rate. The effects of ratio of liquid to solid, leaching temperature, acid concentration, leaching time on Ti leaching rate were studied and the optimal reaction condition was obtained. Roasted titaniferous slag was leaching with 30%(?) hydrochloric acid which ratio of liquid to solid was equal to 8 mL/g, the whole process was keeping 2 h at 120℃, then the leaching rate of TiO2 can reach up to 95%. According to the dynamics equations of layer diffusion control model of solid product and the Arrhenius equation, kinetic equation of leaching in hydrochloric acid system at atmospheric pressure can be obtained with the effect of reaction temperature on leaching rate of Ti and Ca, which is 1+2(1?x)?3(1?x)2/3?11.4e?31.2/(RT)t. Meanwhile, its reaction apparent activation energy is Ea??31.2 kJ/(mol?K).