The invention discloses a multi-functional robot gripper on an assembly line. A horizontal middle installing dish is used as a base body. The top of the middle installing dish is fixedly provided with a gun changing dish installing plate through a vertical transition barrel horizontally. The two sides of the middle installing dish are symmetrically provided with a pair of overhanging clamping jaws through rotating air cylinders. The rotating air cylinders drive the clamping jaws to rotate on the vertical plane so that the clamping jaws can rotate at a vertical state position towards the lower portion or be unfolded at a horizontal state position. The front and the back of the middle installing dish are symmetrically provided with two pushing-pulling air cylinders. Air cylinder rods protrude and extend towards the lower portion on the bottom surface of the middle installing dish and are fixedly connected with a workpiece positioning seat located below the middle installing dish through air cylinder joints. The bottom surface of the workpiece positioning seat is correspondingly provided with a shell body positioning mechanism used for positioning grasped shell bodies and an end cover clamping tool used for grasping grasped end covers. According to the multi-functional robot gripper on the assembly line, the requirements of grasping and carrying in position of different kinds of shell body parts, end cover parts and end cover shell body assemblies are met, and the takt time of equipment can be shortened effectively.