The invention discloses a method for preparing titanium tetrachloride through semi-circulating fluidization, which relates to a method for preparing the titanium tetrachloride. The method takes low-grade high titanium slag and coke as solid raw materials, takes chloride and nitrogen as gas raw materials, and utilizes a semi-circulating fluidized bed to obtain a finished product through a chlorination reaction, cooling and gas-solid separation. The method avoids the agglomeration and adhesion of the particles by circulating coke particles with smaller viscosity and suspending high titanium slag particles with larger viscosity in a fluidized bed reactor, can fully utilize low-grade high titanium slag resource, and has the characteristics of high production efficiency, good product quality, simple and convenient operation, suitability for industrial mass production and the like. The method can be widely applied to the preparation of the titanium tetrachloride by utilizing titanium ore, and is particularly suitable to utilize the low-grade high titanium slag to prepare the titanium tetrachloride.