The invention discloses a rubber feeding device of a motorcycle part assembling machine. The rubber feeding device of the motorcycle part assembling machine comprises rubber fixing columns installed on a rack, a rubber pneumatic sliding table is installed on the rubber fixing columns, a rubber guide rod air cylinder is installed on the rubber pneumatic sliding table, an expansion air cylinder connecting plate is fixedly installed at the lower end of the rubber guide rod air cylinder, an expansion air cylinder is installed in the center of the expansion air cylinder connecting plate, a rubber needle-shaped air cylinder is installed on the right side wall of the expansion air cylinder connecting plate, an expansion pneumatic claw connecting plate is installed at the lower end of a piston rod of the expansion air cylinder, an expansion pneumatic claw fixing frame is installed below the expansion air cylinder connecting plate, symmetric inclined sliding ways inclining inwards are installed on the expansion pneumatic claw fixing frame, and an expansion pneumatic claw is installed on the expansion pneumatic claw connecting plate. In this way, the rubber feeding device of the motorcycle part assembling machine can replace workers to assemble motorcycle rubber, and production efficiency can be greatly improved.