The present disclosure relates to an end effector instrument. The end effector instrument may include an end effector device. The end effector device may include a clip and a resilient portion including a connecting hole and a limiting convex. The end effector instrument may further include a delivery device including a sheath and a shaft. The sheath may include a passage that accommodates the shaft. A distal end of the shaft may include a connecting end. The sheath may include a limiting concave. The connecting end may extend into or exit from the connecting hole when the sheath is set outside the resilient portion: when the connecting end extends into the connecting hole, the resilient portion may expand outward, and the limiting convex may extend into the limiting concave; when the connecting end exits from the connecting hole, the resilient portion may rebound, and the limiting convex may exit from the limiting concave. The end effector device may be operated repeatedly, and the delivery device may be reused.