The global three major processes of titanium dioxide by hydrochloric acid,American ANI,Canadian CTL and Chinese ZLC were introduced. Comparing the characteristics of the three processes,it is believed that the American ANI process and the Canadian CTL process are aimed at extracting titanium,while the Chinese ZLC process achieves effective separation of titanium by extracting iron. In addition,the advantages and disadvantages of these above processes and their application states were analyzed and elaborated. Combined with the current research and development practice,the hydrochloric acid process is still bottlenecked from four aspects: waste acid,cost,equipment selection and the quality of product,which believed that the current hydrochloric acid process is still immature,and no matter which hydrochloric acid process to produce titanium dioxide,it is still in the development stage. Not only the quality of the hydrolyzed titanium solution by hydrochloric acid is not good that fails to achieve the goal of stable production of titanium dioxide pigment,but also the equipment,economy and cost still need to be verified.