i have a character rig animated. I tried to "copy and paste" in curve editor the animation from rig to another one but seems not to be the way.
How can i transfer animation from a rig to another?
If (and only if) both rigs have the same structure, with same bones naming, so you can:
And that's it! Your second rig should have exactly the same animation as the first one.
Be aware that if you change something in the first rig's animation, it will also change the second's one, since they share the same action. To avoid this, you can click on the "2" button (or any number that shows the number of users you have for the action) to make a single-user copy of the action and have two independent actions:
To build on the accepted answer: If you want to import from a separate file, you can link and append Actions from another .blend and it will show up in the action list as described before.