public Transform target;

public float moveSmooth=5f;

Vector3 offset;

void Start () {

offset = transform.position - target.position;//获取相对位置

}

void Update () {

Vector3 targetPostion= offset + target.position;

transform.position = Vector3.Lerp(transform.position, targetPostion, moveSmooth*Time.deltaTime);

// transform.position = targetPostion;

}