I'm making a total conversion mod, that will feature new non-human race. My race has more long arms and shorter hips. I attempted to rig this to standard skeleton, edited with NifScope (just moving positions of bones). But installed as new race in CK, it turns into standard human skeleton while playing animations.
How can i create new playable race with modified skeleton without making complete new animations?

Far as I'm aware, you can't. Bone names and absolute positions during translation are integral to their animation process. I'm not an animation guru, but that's how a lot of "canned" animations work, which most of these are. There are very few actual "havok" animations in the game that use procedural data to generate the animation, like velocity and force vector.

Thanks for answer, but I think I can do that. Scaling bones instead of moving its positions does affect the animations in-game!
I just tested it on standard skeleton (scaled one bone) and it works fine: one arm really became larger. Then I used this method on all bones to fit my race model. And its works very nice.