The invention relates to a method for preparing bio lubricants through catalytic hydrogenation of biodiesel. The method comprises the following steps of enabling the biodiesel to be in contact with a catalytic hydrogenation catalyst under the condition of a catalytic hydrogenation reaction so as to generate a hydrogenation saturation reaction and an ester-interchange reaction, and enabling reaction effluents to be subjected to reduced pressure distillation, so as to obtain bio lubricant components. The catalytic hydrogenation catalyst contains a copper compound, a zinc compound and aid components which can be selectively added, wherein the aid components are selected from one or more of aluminum compounds, zirconium compounds, magnesium compounds, and chromium compounds. Through the adoption of the method provided by the invention, the bio lubricant components with stable performance can be obtained. The method provided by the invention is simple in technology, and target products are good in selectivity and high in yield. In addition, the bio lubricant components are from the biodiesel prepared from animal and vegetable fat or waste fat and have favorable biodegradability.