XDJM,

I had an interview May 24th, and the hiring manager called me last week and
said
that they are in the process of giving me an offer. But the offer needs to be
sent out from HR people since HR still have to do background and reference
check, etc. So he said he only gave me an oral offer, not an official offer.
But I called HR today and HR said the manager has not decided yet about the
offer.

so is the Hiring Manager just kidding?

what should I do upon this issue? email Hring manager and say I'm sooooooo
eager about this work? or any suggestions?

//bow

just wait and relax. In some companies, HR staff will finish reference and background check first, and then they can give your offer. Before that, they won't tell you anything about the offer. BTW, don't call HR people again. I know a lot of HR people are very mean to foreigners since they don't want them to make troubles in the future about some immigration stuff. Sometimes, they will try to pursuade the department manager to change another person. Hehe, sorry if I scare you.