1, Go to a public notary ( mostly also a lawyer), and he'll print a paper, which indicates your personal status, and ask you to sign in front of him. Then he makes a certificate. (you can find a public notary in yellowpages.)
2, Go to the provincial government to authenticate your certificate. (You may ask the lawyer for the address.) This takes $16 in Ontario.
3, Go to the China's consulate for the final step.
4, When you get to China, have all your stuff translated into Chinese.