This maybe not the answer to poster's question.But this may helpful to people whose face same situation with me:
The client have two network cards,a wireless one and a normal one.
The ping to server can be succeed.However telnet serverAddress 3306
would fail.
And would complain
Can't connect to MySQL server on 'xxx.xxx.xxx.xxx' (10060)
when try to connect to server.So I forbidden the normal network adapters.
And tried telnet serverAddress 3306
it works.And then it work when connect to MySQL server.