The invention discloses an idler gear shaft component which comprises an installation boss, an idler fear shaft and a baffle; the installation boss is formed after being directly cast and machined on an air cylinder body, and the installation boss is provided with a positioning hole; the idler gear shaft is provided with a shaft neck for installing an idler gear, and the center of the head of the idler gear shaft is provided with a positioning boss matched with a positioning hole; the baffle is of a round-cake-shaped structure, the center of the baffle is provided with a positioning through hole, the idler gear shaft penetrates through the positioning through hole from the positioning boss and then is inserted into the positioning hole, and the idler gear shaft is fastened to the installation boss through bolts under abutting of the baffle. By means of the idler gear shaft component, the weight and cost of the air cylinder body can be reduced.