I am overseas. I have tried to ask Universities for getting advices about PhD studentship. Most of them did not reply me.:( Only SouthamptonU told me that full funding can be provided for overseas. So I applied, got the offer. My supervisor then applied ORS for me. But it failed and he couldn't help me anymore. So I can't join. For our overseas, it seems that funding source is too limited. If ORS is failed, we bascially cannot get any money. Anyway, do you have any advice to secure the funding for my PhD study in next time?

Sorry that you were unable to find any help towards funding this time. Try the funding section of this site for information and links. The Department of Education in your home country may have some advice for you (they may even provide scholarships). Also try the British Council who may also be able to help with scholarship advice.