主要问题是循环

while (Vector3.Distance(transform.position,targetPosition) > 0.1f)
{
    float step = speed * Time.deltaTime;
    transform.position = Vector3.MoveTowards(transform.position,targetPosition,step);
}

这一步移动了对象，因为同时没有渲染任何帧。 while会阻塞整个线程，直到完成为止（我在这种情况下还不算太长），然后在完成后渲染帧。

此外，在注释OnGUI中也提到，每帧被多次调用，因此情况甚至更糟。

正如我也评论过的，OnGUI是一种遗产，您不应该再使用它，除非您确切地知道自己的工作方式和作法。

请使用UI.Button in a Canvas。

如果我没看错，您想在按住按钮的同时移动。

不幸的是，没有内置的Button可以处理“按下按钮时保持按下状态”之类的东西，因此您必须使用IPointerDownHandler和IPointerUpHandler界面。

将此类放在UI.Button对象上

public class MoveButton : MonoBehaviour,IPointerEnterHandler,IPointerExitHandler,IPointerDownHandler,IPointerUpHandler
{
    public enum Alignment
    {
        Global,Local
    }

    // Configure here the movement step per second in all three axis
    public Vector3 moveStep;

    // Here reference the object that shall be move by this button
    public Transform targetObject;

    // Configure here wether you want the movement in
    // - Global = World-Space
    // - Local = Object's Local-Space
    public Alignment align;

    private Button button;

    private void Awake ()
    {
        button = GetComponent<Button>();
    }

    //Detect current clicks on the GameObject (the one with the script attached)
    public void OnPointerDown(PointerEventData pointerEventData)
    {
        // Ignore if button is disabled
        if(!button.interactible) return;

        StartCoroutine (Move());
    }

    public void OnPointerUp(PointerEventData pointerEventData)
    {
        StopAllCoroutines();
    }

    public void OnPointerExit(PointerEventData pointerEventData)
    {
        StopAllCoroutines();
    }

    // Actually not really needed but I'm not sure right now
    // if it is required for OnPointerExit to work
    // E.g. PointerDown doesn't work if PointerUp is not present as well
    public void OnPointerEnter(PointerEventData pointerEventData)
    {

    }

    // And finally to the movement
    private IEnumerator Move()
    {
        // Whut? Looks dangerous but is ok as long as you yield somewhere
        while(true)
        {
            // Depending on the alignment move one step in the given direction and speed/second
            if(align == Alignment.Global)
            {
                targetObject.position += moveStep * Time.deltaTime;
            }
            else
            {
                targetObject.localPosition += moveStep * Time.deltaTime;
            }

            // Very important! This tells the routine to "pause"
            // render this frame and continue from here
            // in the next frame.
            // without this Unity freezes so careful ;)
            yield return null;
        }
    }
}

或者，您可以坚持自己的代码，但可以将按钮与移动分开，例如

private bool isPressed;

private void OnGUI()
{
    isPressed = GUI.Button(new Rect(165,300,150,350),"right");
}

private void Update()
{  
    if(!isPressed) return;

    var pos = transform.position;
    var targetPosition = pos + Vector3.right * 0.5f;

    if (Vector3.Distance(transform.position,targetPosition) > 0.1f)
    {
        float step = speed * Time.deltaTime;
        transform.position = Vector3.MoveTowards(transform.position,step);
    }
}