Abstract: To solve the easy sticking of the particles in the chlorination of modified titania-containing blast furnace slag, the mechanism of preventing the sticking by additives was studied by XRD and thermodynamics analysis. Meanwhile, the effects of temperature, excessive carbon content, gas flow rate (N2+Cl2) and chlorine partial pressure on the chlorination behavior were investigated. The results showed that the prior reaction of phosphoric acid as an additive with CaO occurs to form Ca3(PO4)2 with a high-melting point, and the latter reacts with CaCl2 to give Ca5(PO4)3Cl. Thereby the sticking of the particles caused by the aggregation of low-melting point calcium and magnesium chlorides is avoided. The best chlorination results are obtained at 850~900°C with the excessive carbon content of 15%, the flow rate of 400 mL/min and the chlorine partial pressure of 40 kPa, and the chlorination ratio reaches 90.8%~93.5% in 60 min.