Welcome to the forum, Hongyuan. Your written English is pretty good, so you obviously have a good grounding in it. There are no secrets to developing fluency- you simply have to practise a lot. We'll happily try to help, and here are some sites that might be useful for listening skills: http://www.usingenglish.com/links/Listening/index.html
Have as much contact as you can with speakers of English, as you can here, and get used to the ways we use the language.