The invention discloses a snap ring pressing mechanism. The mechanism comprises a cylinder located at the intermediate position of the mechanism, a coaxial assembly coaxially arranged with the cylinder and two sets of pressing devices symmetrically arranged on both sides of the cylinder. The coaxial assembly comprises a support plate, a pressing block, a pressing bar and an upper support plate which are connected to the upper end of the cylinder sequentially, a pressing support plate located above the support plate and at the periphery of the pressing block, a base plate at the lower end of the cylinder and a snap ring pressing tool located under the base plate and connected with the support plate. Each pressing device includes a lower connecting rod, a middle connecting rod and an upper connecting rod for connection, and further comprises a proximity switch sensing rod sleeved on the pressing support plate and the support plate and a spring and a proximity switch which are connected onto the rod. The snap ring pressing mechanism achieves automation of the pressing, and is high in pressing efficiency. The pressing direction is guided accurately, and the pressing is stable and accurate. The pressure sensor controls the pressure within the set range. The mechanism can sense a snap ring automatically to ensure that the snap ring enters a snap ring groove. The pressing positioningis accurate. The structural components are rigorous and reliable, and the device performance is stable.