If you don't care about the qq.com domain indexing you, you can block them from indexing your site. Just check the source/referral and block them.
As others said, a recaptcha will help and Google has a great one! Enable it on your comments and contact form and you'll shave the spam down to minimal numbers.
But if qq.com is hitting your server and wasting server resources, it's best to block them at a firewall level.