Thank U for your respond..

I've try your code, and that's great!  

But still, i have some question..

1. Does it mean we don't have to set a Save Directory?

Just like an example in the document :  uploader.SaveDirectory="/myfolder" 

2. If we don't have to set a Save Directory, where does the file location of my uploaded file before I copy/move it?

3. If we upload two or more files with the same name,  will it replace the other files?

Because my site sometimes have 100-1000 concurent users that upload files.

Thank U