The invention discloses a clamping-cutting-grasping multi-functional engineering attachment applying single-degree-of-freedom shape-shifting mechanism, with a symmetrical structure, including a clamping and cutting device, a grasping device, and a separating and deforming device, and further includes two hydraulic cylinders, one base, two separation bases, a driving hydraulic cylinder, hydraulic scissors, a grasping connecting rod, a grasping claw, a separating connecting rod, a base guide rod, a base slider, a separating slider, first connecting rod, second connecting rod and separation slider track groove. The invention uses a double slider mechanism to achieve the relative movement between the grasping device versus the clamping and shearing device, and also realizes a fast conversion from clamping and cutting device to the grasping device, all the work requirements being satisfied under each working state without motion interference.