I moved here from CA, Do I need to change my Driving license to OK one?

Eventually, yes.

(Have fun at the DMV, by the way. I was at the one in Edmond last week to renew my expired license. Got there at 8:00, right when they opened, and it was 10:00 before I got outta there. Apparently they were having massive computer problems all week long. Good times.)

(And bring some reading material. I wish I had.)

Tnx man,
how long I can use CA lic here ?

Until it expires? No idea.

(Mainly I just wanted to gripe a little about the DMV, and this was as good an opportunity as any. Sorry.)

I would recommend contacting OKDPS (Oklahoma Dept. of Public Safety) for more precise answers, but here's a link to the FAQ section of their web site:

http://www.dps.state.ok.us/dls/dlfaq.htm

For those that don't want to click on the link, here's the excerpt from the FAQ:

Q. How do I transfer a valid (not expired) license from another state to Oklahoma?

A. Upon establishing residence, new residents who own vehicles that are in Oklahoma are required to register all of their vehicles in Oklahoma before they apply for an Oklahoma driver license. Upon the completion of registering your vehicle(s) (if applicable), and if your license from another state is valid, take it along with a second approved form of identification to a Driver Examiner. The written and driving test may be waived if department standards are met. If you possess an out-of-country license please contact a Driver Examiner to find out if the tests can be waived.

30 days is the law. After moving to the State of Oklahoma you have 30 days to transfer your license. Do not let your other license expire like I did or you will be required to take both a driving and written test.