Hello, I want to do item class and I want to use it with blueprint and my character have some items. If I use actor class for derive my item class, I can use my items in blueprint but I couldn’t put item to my character without adding a scene. What can I do? I change base class or ?
Yes, you can use Actor type for Item class.
I don’t know if i understood correctly, but if you want to use blueprint (for example put your item to inventory), you must spawn it first somewhere in your world. Classes are only a “templates” for creating objects - and to use specific object, it must be created (spawned) first. (for example using Spawn Actor From Class)
So, let’s say you have “Item” class and “Potion” child class. Then you create “HealthPotion” blueprint based on Potion class and set up its model, statistics, etc. In order to use (drink) this HealthPotion, it must be spawned first, either by dragging it into scene or spawning from class in blueprint. That’s because you want to use object of HealthPotion class, not HealthPotion class itself 
Here is a tutorial from Epic Games on Inventorys: