I don't know what the regulations/difficulties are around registering domain names where you are, so excuse me if I suggest something not possible there. I am also not familiar with what is "standard practice" there.

The domain name is just a pointer to the webserver whose "real name" is a number like 111.222.333.444. You can even use the webserver software itself to point a domain name to a different directory or application on the server. So, first, I would suggest getting more than one name, maybe some are pointing directly to the English version of the site.

Your current name seems very cryptic to me. If I know the name of your company is Beijing T-Win, I wouldn't guess t-win21cn and once I had found it, I wouldn't remember it. It would be good if customers can find your website without having to carry the name around on a piece of paper. I can see where the cn comes from (if this is a common practice there), but the 21 has me completely baffled. beijingt-win, t-win, t-winbeijing, t-winconsulting, twinbeijing, or beijingtwin would be very good.

Another type of name would be to refer to your product/service name. Your www.interbook.cn is very good in this respect. You don't want it too generic as this may make it easy to "accidentally" find one of your competitors, i.e. if you have translator.cn and your competitors have translation.cn, part of your business may disappear. On the other hand, you may want to snap up some of these overly generic names yourself to "steal" business from your competitors, but I wouldn't use them for the main name you give out. The site name needs to be something, or at least related to something, that you are going want to use prominently in your marketing materials, so I don't feel that I can suggest what that should be. Like the text you posted says "T-Win Interbook" several times, that would make me guess t-wininterbook and interbook and sure enough I would find interbook.

I agree with TEd that there is way too much information on your first page and the cutesy stuff is very cliche'd (there's a floating menu of some sort on the Chinese page that is almost as annoying as the cursor clock). The type of information you are showing would normally be several pages of information under a menu item of "About Us" or "Our Company. The first page of the English site looks like a document that you just pasted in rather than a professional web site. The Chinese site is better but still too long for a first page(I don't understand it, but it looks organized), but a first time visitor is not likely to notice anything that you have to scroll down to see.

This sentence I don't understand at all: "In most cases the translation of books is a type of written translation."

"T-Win Interbook will translate catalogues of publishers and summary of some of their books into English or Chinese and recommend them to purchasing publishers." - should say either "the catalogues of publishers" or even better "a publisher's catalogues", "and a summary ...". Catalogues of publishers could be a list of the names of publishers rather than a list of each publisher's books.