The invention discloses hydrogenation catalyst impregnating liquid and a preparation method thereof. The composition of the impregnating liquid is shown as follows: the active metal content is measured by oxides: a group-VIB metal oxide is 5-70 g/100 ml, a group-VIII metal oxide is 1-30 g/100 ml, the molar ratio of organic acids to group-VIII metal atoms is 0.1-1, and the molar ratio of organic amines to group-VIB metal atoms is 0.1-2. The preparation method comprises the following steps: simultaneously adding cobalt/nickel salt and the organic acids in water, slowly increasing to a certain temperature till complete dissolution, keeping a constant temperature, adding the organic amines, continuously stirring, keeping the temperate, adding molybdenum/tungsten salt, continuously stirring andobtaining the hydrogenation catalyst impregnating liquid after complete dissolution for preservation and later use. In the method disclosed by the invention, group-VIB metal salt and group-VIII metalsalt are dissolved according to a certain procedure, so that the metal concentration and the stability of the impregnating liquid are improved; in the whole preparation process, ammonia water is notused, so that the environmental pollution is reduced.