The utility model discloses a three jar bent axle variation die surfaces forge base spare, including first body, the shaping is is outwards forged and pressed at the first body both ends has a plurality of first horizontal equilibrium boards, and the forging and pressing shaping of first body middle part has a plurality of first vertical balance plates. Still disclose one kind in advance, the blank structure of finish forging includes the second body, the forging and pressing shaping of second body both ends has a plurality of second horizontal equilibrium boards, the forging and pressing shaping of second body middle part has the vertical balance plate of a plurality of seconds. Owing to three jar bent axle variation die surfaces forge the integrative forging shaping of the first forging die of base spare adoption, just the first first die joint of going up mould and first lower mould is the plane, and the blank was difficult for deflecting at the forging initial stage, had improved the stability of forging technology. In advance, the blank structure of finish forging adopts that the second forging die is integrative to forge the shaping, and mould and second lower mould are in on the second the vertical balance plate of second department adopts the ladder die joint to full state is filled to the die cavity that reaches the vertical balance plate of shaping second, and then has improved the utilization ratio of material.