welcome to a2k , liuwei851126 !
you needn't be overly concerned about the different pronounciation of english/english viz. american/english .
i'd suggest you sharpen your listening skills , that should help greatly with pronounciation .
if your computer can can receive 'sound' , i would suggest you go to the
...BBC RADIO SITE... (click on the link and follow the lead on the right side of the BBC site).
you can also listen to BBC shortwave radio if you have access to it .
finally you might consider trying to obtain cd's of "spoken words" - cd recordings of classical british plays would be good - do you have access to a library that can lend them to you ?
hope this helps .
(english is not my first language , so you may find some errors in my answer).
let us hear if you are successful .
hbg