Can RPC only use in GameThread? So How can I send message to server in AnimNode?

Using a character class reference call an event in the character class that handles the RPC.

Thanks, You mean “Event Loop”? Like this:

AnimNode_XXX
{
    UpdateAssetPlayer(const FAnimationUpdateContext& Context) {
         ActorComponent->Event += event;
   }
}

ActorComponent
{
    TickComponent(float DeltaTime, enum ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction)
   {
         for(e in Event){
            Excute(e);
       }
   }
}