The invention relates to a kind of hydrogenating protectant as well as its preparing method. The protectant contains aluminium oxide carrier on which there's active hydrogenating metal and halogen. The content of the halogen (by element on the base of the catalyst) is 0.5-10wt% and the specific surface area of the carrier is 2-50m2/g, the pore volume is 0.4-1.2ml/g. The ingredient of the carrier:one kind or many kinds of aluminium oxide and/or the predecessor of aluminium oxide, at least one kind compound that contains halogen. After mixing, shaping and calcinating the producers can get the carrier. Compared to the present hydrogenating protectant, the invention has higher de-metal activity and stability.