The invention discloses a method for preparing TiCl4 through titanium-contained slag. The TiO2 content in the slag is 30 to 45 percent. The method is characterized in that the titanium-contained slag is directly reduced at a high temperature; and the reduced slag is used to prepare the TiCl4 through low-temperature boiling chlorination. According to the method, the titanium-contained slag, a reducer and a binding agent are mixed evenly and are used to make pellets; the pellets are reduced at the high temperature; the reduced pellets are crushed after being cooled down; and then the TiCl4 is obtained through the low-temperature boiling chlorination. The method has the advantages of low reducing temperature, short technical process, high total titanium recovery rate, and the like.