The invention relates to the field of mounting of accessory facilities of a blast furnace and discloses a mounting method for a crane beam on blast furnace top. The mounting method comprises the following steps: a, assembling inclined struts and the crane beam according to a design drawing, hoisting the crane beam on the inner side of a frame, combining and assembling the crane beam on the outer side of the frame and an accessory structure of the crane beam as a whole, and combining and assembling the two inclined struts by using a connecting piece; b, hoisting the inclined struts, temporarily fixing column bases of the inclined struts of the crane beam after positioning the inclined struts, and connecting a steel wire rope in the middle parts or the upper parts of the inclined struts to temporarily fix the inclined struts; c, hoisting the crane beam on the outer side of the frame, controlling the elevation of the crane beam through a level instrument, controlling the straightness of the crane beam through a theodolite, connecting the inclined struts and the crane beam after alignment, and releasing hooks after firm welding; and c, mounting other accessory structures. The method can effectively prevent the crane beam from downwarping, is high in mounting precision, and is particularly suitable for a structure, in which the overhang length of the crane beam is greater than the length of the crane beam in the frame.