The invention discloses a carbide-reinforced cobalt-based composite material for a wear-resistant rotating shaft and a preparation method thereof, and belongs to the field of high-temperature wear-resistant alloys. The material base body alloy comprises the chemical components of 18-34% of Cr, 9-28% of W, 0-6% of V, 0-10% of Ni, 0-10% of Fe, 0.2-2% of C, and the balance Co, wherein the main reinforcing phase of the material is the M6C type and M23C6 type carbide, and the composite material is prepared by a powder metallurgy method. According to the composite material and the method, the Co-based alloy containing the high-melting-point elements of W, Cr, Ni and the like is selected to be the base body, so that the composite material has the performances of high temperature resistance, corrosion resistance and wear resistance; a proper amount of WC powder is added into the cobalt-based alloy base body, through the high-temperature phase change of the WC, the M6C enhanced phase is formed,and the hardness and the wear resistance of the cobalt-based alloy are greatly improved.