The invention provides a method for preparing carbon-doped titanium oxide or / and titanium carbide from titanium-containing mineral or slag. According to the method, the cheap titanium-containing mineral or slag is adopted as a donor of the titanium element, and hydrogen and methane are selected to serve as a reducing agent and a carbonization agent respectively, so that raw material cost is saved; moreover, the processing only needs to reach the low temperature of 1,200-1,400 DEG C, meanwhile, reforming of methane is realized in the process of preparing carbon-doped titanium oxide or / and titanium carbide, hydrogen and carbon black are obtained through methane splitting, hydrogen and the titanium-containing material are subjected to a gas-solid reduction reaction, and reduction efficiency is high; meanwhile, the carbon black obtained through splitting greatly improves carbonization efficiency, carbonization temperature is low, the carbonization rate is high, energy consumption cost is saved, therefore, production cost is lowered, the production reaction rate is increased, the recovery rate of the titanium element in the raw material is raised, and the problems that in an existing carbon-doped titanium oxide and titanium carbide production process, preparation temperature is high, production efficiency is low, and cost is high are well solved.