If you receive crashes, you're doing something wrong.
If you receive a NullReferenceException, likely in OnEnable() your references like Idleanimator.AnimationState are not set up yet. If you're using recent spine-unity versions, accessing skeletonAnimation.AnimationState will initialize it automatically, while on older versions you will need to call skeletonAnimation.Initialize(false);.

What does the crash say, or what is the exception message saying?

Noticing the lines:

Idleanimator.AnimationState.Start += JumpMethod;
..
attackAnimator.AnimationState.Complete += AttckAnimalComplete;

What is Idleanimator and what is attackAnimator? Are they separate SkeletonAnimation instances? Are you sure that you want to have multiple SkeletonAnimation objects and not a single one which plays all animations?

Note that you can also register events to a single TrackEntry after starting or adding an animation

Spine.TrackEntry trackEntry = animationState.SetAnimation(trackIndex, "attack", true);
trackEntry.Start += OnSpineAnimationStart;

(See the documentation here or in English here)

fengmin I should have told you this earlier, but there is a translation button on the forum so you can post your reply in your native language.

It looks like you didn't answer Harald's question. Please tell us what Idleanimator and AttackAnimator do.
Are you trying to have multiple SkeletonAnimation objects?

If you want to handle the events of the idle animation and the attack animation separately, as Harald suggested, it would be best to use TrackEntry to register only the events for specific animations. Have you tried the code Harald suggested?

fengmin So, could you show us what the AttckAnimalComplete method does?

fengmin Is there any reason why you are using ClearTracks()? As long as you are using SetEmptyAnimation(), I don't think it's necessary, and I guess it might cause the crash.

After trying this, Unity froze even if I just called SetEmptyAnimation() on both the Complete and End events, so it seems that the problem is not ClearTracks(), but that you are trying to do these operations on both Complete and End. In fact, I think there is usually no need to call this on both Complete and End, so why is it necessary on both? If you want to call the method when the loop is complete, register Complete, and if you want to call it when the playing animation switches to another animation or finishes playing, register End should be sufficient.

fengmin Unfortunately, I'm not sure why the crashes occur, but I think Harald will answer that later.

Anyway, I think there are some solutions. For example, you can modify the code to register a handler for the End event of the TrackEntry and call AddEmptyAnimation() beforehand so that the animation returns to the setup pose when it is complete.

        Spine.TrackEntry trackEntry = attackAnimator.SetAnimation(0, "attack", false);
        trackEntry.End += AttckAnimalComplete;
        animationState.AddEmptyAnimation(0, 0, 0);

This way, the End event is fired when the animation switches to the empty animation, so it is sufficient to simply register a method to the End event. This allows you to cover both the case where the animation is complete, and the case where the animation is switched to another before it is complete.

fengmin Oh, sorry, I forgot to add that I assumed that the AttckAnimalComplete() would be like this:

void AttckAnimalComplete(Spine.TrackEntry trackEntry) {
   isAttk = false;
   isAttked = true;
   playerState.playerState = CharacterState.Idle;
   attackAnimator.state.SetEmptyAnimation(0, 0);
}

Please note that ClearTracks() does not reset the pose of the previous animation. This is explained in the API reference: https://esotericsoftware.com/spine-api-reference#AnimationState-clearTracks
So you should use SetEmptyAnimation() instead of ClearTracks().

Misaki After trying this, Unity froze even if I just called SetEmptyAnimation() on both the Complete and End events, so it seems that the problem is not ClearTracks(), but that you are trying to do these operations on both Complete and End.

@fengmin Note that SetEmptyAnimation() or SetAnimation() in general is also triggering End and Complete callbacks. You're creating an infinite loop if you call SetEmptyAnimation() or SetAnimation() from a callback of AnimationState.End or Complete. You need to either register to callbacks of a single TrackEntry like trackEntry.End += YourCallback or use AddEmptyAnimation() as Misaki mentioned above.

@fengmin You can use trackEntry.IsEmptyAnimation.
http://esotericsoftware.com/spine-api-reference#TrackEntry-isEmptyAnimation

In general as Misaki pointed out already, it would be far more recommended to call AddEmptyAnimation() directly after setting e.g. the attack animation.

Also, it would likely be better to call attackTrackEntry.Complete += AttckAnimalComplete instead of registering it at animationState.Complete += AttckAnimalComplete, as you then receive the callback with every completed animation and not only your attack animation.