Perovskite is the inevitable phase formed in the cathode during electrolysis of TiO₂ in molten CaCl₂ by FFC Cambridge process. Dependency of perovskite in the cathode on gases released from the anode in the process of the preparation of titanium is studied. The results show that three stages is obtained based on the phases formed in the cathode including formation of perovskite, deoxygenation from perovskite and titanium suboxides to TiO and deoxygenation from TiO to Ti . Perovskite formed in the cathode is close related with gases released from the anode although the decomposition voltage is lower than that of CaCl₂. Chlorine releases from the anode due to overvoltage which is caused by the formation of perovskite in a short time. Amount of chlorine is depended on the mass of TiO₂ and generation of different titanium suboxides during electrolysis process. The mass ratio of TiO₂ and chlorine is from 9:2 to 46:2 when titanium suboxides are between Ti₃O₅ and TiO at the first deoxygenantion stage. The anode is no obvious consumption during chlorine releases. Formation of the perovskite and deoxygenation of Ti₂O are the main limited step to prepare titanium by electrolysis process in molten CaCl₂. The total current efficency from TiO₂ to Ti is 24.07%. The current efficiency of the first stage is between 22.37% and 44.74% and the second stage is between 30.18% and 37.72%.