Abstract: The cooling treatment of titanium slag has an important influence on the subsequent titania pigment production.In this paper,the effect of cooling method for titanium slag,including granulating,water cooling and air cooling,on the compositions,phase and acidolysis performances of titanium slag was investigated.It is found that the titanium sesquioxide content in the slags is decreased using the cooling treatments mentioned above,of which the granulated slag has the lowest content of Ti₂O₃.The main phases are TiO₂ and （FeMg）_xTi_yO₅ in the cooled slags.The crystal form of TiO₂ is rutile in granulated slag but anatase in water cooling or air cooling slag.The acidolysis rate of cooled slags is all less than that of the industrial titanium slag. The acidolysis rate is 90.61% and 92.46% for the water cooled slag and air cooled slag,respectively.However,the acidolysis rate of granulated slag is only 74.72%,about 20% less than that of industrial titanium slag.