The invention relates to a sliding plate for off-line baking a continuous casting ladle and a molten steel outlet replacing method, belonging to the technical field of steel-making sliding molten steel outlet processes. The method is characterized by comprising the following steps: firstly, placing a ladle sliding molten steel hole at a baking position for baking and standby after blowing oxygen and firing and washing without dismantling a used sliding plate and a molten steel outlet; dismantling the used sliding plate and the molten steel hole before the ladle is planned to be input and used, and then arranging a new sliding plate and a new molten steel outlet so as to lead the ladle to be normally produced on-line. Because of adopting the method, the problem of the heavy accident of ladle penetrating caused by not opening the sliding plate due to long off-line baking time during interrupted production of a continuous casting machine is solved. The method can prolong the use continuous time of the sliding plate and the molten steel outlet by 3-4 furnaces, realizes secondary utilization of the sliding plate and the molten steel outlet after the use, and can lower the cost of steelof the sliding plate and the molten steel outlet per ton by more than RMB 0.5yuan.