I need to hook a service function in KeServiceDescriptorTable by number and i know that i can find the offset of SDT with KTHREAD struct. How to find offset of KTHREAD in windows x64?

First off, IA-64 is Itanium 64 which is very different architecture than x64 (aka x86-64, aka amd64, aka EMT64).

To answer your question, you can download the public symbols to get the layout of the KTHREAD structure for a particular build of Windows.

I have a hard time reading your post and therefore I am unsure if I've answered it fully. You can try rewriting your post in a more coherent manner.