The invention relates to an initial hydrothermal deactivation method for a selective hydrogenation nickel catalyst. The initial hydrothermal deactivation method mainly comprises the two processes: (1) reducing a catalyst, wherein the nickel element in the reduced catalyst exists in a way of elemental nickel; and (2) carrying out hydrothermal deactivation treatment on the reduced catalyst, namely filling a reactor bed layer with the catalyst, introducing water vapor with a certain temperature to a catalyst bed layer, and sufficiently contacting the water vapor and the catalyst to finish the hydrothermal deactivation treatment process of the catalyst. The method has the characteristics of simplicity in operation, environment friendliness and short treatment period. In addition, the influence to the use stability of the catalyst is relatively low when the method is used for carrying out initial deactivation on the catalyst.