Abstract: A dust-proof cover made of rubber comprises an elastic telescopic section including a plurality of axial enhancing ribs; a combining portion including a first combining section, a second combining section, and a third combining section; two buckling strips being included. An inner side of each of the second combining section and third combining section has a buckling strip; each buckling strip having a chamfered corner for guiding the installation of the transmission shaft unit so as to enhance the coupling of the dust-proof cover and the transmission shaft unit. Two buckling strips are formed on an inner surface of the first combining section; each buckling strip having a respective chamfered corner for buckling an outer lateral side of the transmission shaft unit so as to buckle the transmission shaft unit. A plurality of axial and radial texture are formed on the inner surface of the first combining section.