The utility model discloses a two-station mechanism for machining main bearing seat, oil grooves and tile grooves. A milling head is horizontally provided with a station I and a station II, wherein, a cutter holder of the station I is provided with eight inserted-tooth two-edge cutters and five groove milling cutters. The cutter holder of the station II is provided with five groove milling cutters. Each cutter holder is provided with a sleeve gasket which adjusts an axial position of the cutter. Through special setting to the milling cutter, the two-station mechanism realizes one-time machining to eight side surfaces of a main bearing seat of a four-cylinder diesel engine, oil grooves and tile grooves. Furthermore the two-station mechanism has the following advantages: effectively reduced machining cost, high machining precision and high operation efficiency.