I am in LAN(through a router to visit internet),I set up a dns server,doamin name is wb.com
for example, host 192.168.0.4 is xsb.wb.com,
WAN interface ip of router is 217.77.124.94

how can I do to achieve that resolve xsb.wb.com to ip 217.77.124.94 in LAN

If you are trying to set up the PC's on the local LAN to resolve "xsb.wb.com" to 217.77.124.94 and your local subnet is 192.168.0.0 then it won't work very efficiently. A better solution might be to alter the local PC hosts file and reflect that "xsb.wb.com" is really 192.168.0.4. If you try and have the dns resolve to the public IP it will go out the router to the world and then turn around and come right back in again and it might end up in a loop. The other alternative it to set up a LAN based dns if you don't want to change the hosts file.

Excuse my "language", but WTF are you trying to do? -- "wb.com" comes up as http://www2.warnerbros.com/main/homepage/homepage.html in my browser, while whois says that "217.77.124.94" is located in Russia.

At the very least, you should never use a real domain name on a LAN unless you actually own it.

For home lan I usually use .dom instead of .com that way I don't have to worry about stepping on another real domain.

mydomainname.dom

I use ".lan" -- same reason, same effect.

I think all the .{a..z}an "TLD's" should reserved for private use.