How to custom UI location?

I'm start learning how to create gui for Linuxcnc with glade and python.

First i want to put all python file of UI in one folder, but i dont now how to config Linuxcnc load UI from that folder and relative python file in there?

Might I suggest you use gscreen to load your UI and gscreen handler file to write your python code.
linuxcnc.org/docs/2.7/html/gui/gscreen.html

It's not super well documented but does give some basic examples in the docs.
I might add that the sample screens of gscreen's are mostly all development vehicles - they don;t always show the easiest way of doing things ( as it was a learning process).
It's easy to start with just a GLADE ui file and have gscreen display it by naming it tester (see the docs)

for instance gscreen will give you these variables for config location:

self.data.CONFIGPATH - folder from the launched configuration
self.data.SKINPATH - folder from of the avaliable skins
self.data.BASE -the base location of linuxcnc (this changes if you use RIP vrs installed )

I'm willing to add more docs of gscreen based on questions I get - gscreen's purpose is to facilitate custom screens.

If you are dead set on doing things yourself then I suggest you look at gscreen or gmoccapy code as they both can be used as example code of how to do things for GUI display.

Chris M