This paper proposes an effective strategy of holding a swinging object by two arms for automating heavy parts assembly. Instead of human arms, this research uses two flexible arms to avoid impact forces at the moment of contact. The strategy has three modes, which are following, approaching and cooperation. One arm which touched the target object first follows the object so as to keep the contact. From the position and the deflection of the arm, the exact position of the object can be measured. In the approaching mode, the other arm is also controlled to touch the object by the feedback of the distance to the object. After the holding, two flexible arms reduce the vibration of the object by cooperative control. All the modes are realized by the same structured controllers, which control the desired force generated at the tip and the position. Experimental results show the effectiveness of the strategy.