The invention discloses a temperature-controlling chrome-protecting method for an ultra-low carbon high chrome steel RH decarbonization process. The temperature-controlling chrome-protecting method for the ultra-low carbon high chrome steel RH decarbonization process comprises the following steps of S1, setting the RH feeding molten steel temperature to be 1605 to 1625 DEG C, enabling molten steelto contain the following chemical components in percentage by mass: 0.05 percent to 0.5 percent of Si, 0.5 percent to 2.0 percent of Mn, 5 percent to 15 percent of Cr, and 0.1 percent to 0.35 percentof C, and vacuumizing after a steel ladle is put in place; blowing oxygen, decarbonizing, and the like. The temperature-controlling chrome-protecting method for the ultra-low carbon high chrome steelRH decarbonization process provided by the invention has the advantages that after RH oxygen blowing and decarbonizing are finished, the C content reaches to the target ingredient, the oxidation lossof the Si and the Mn in the molten steel is lower than 15 percent compared with RH feeding, and the content of the Cr element is reduced to be smaller than 0.5 percent.