visiting China from Toronto, so visa requirements

Generally speaking, you need to ask your partner to provide you an invitation letter. With the invitation letter, your valid passport and application form with recent taken photos, you can apply for a F/M type for your business trip to China. With it, you can see your friend, too.

Thank you for answer.

Is invitation letter just an informal letter written by her (my friend) or it has to be official. If official where does she obtain this letter. She lives and works in Hongkong but has a home in Dalian where we both will meet.

Since you still want go on business and apply F/M type, the invitation letter should be provided by your business partner in China such as a company instead of your friend. It should be a formal one.

However, if you just go to China for some investigation without a partner company in China, you can ask your friend to write you an informal invitation letter. Then you can apply a common Tourist L type to China to see your friend and meanwile investigate the Chinese market. BTW, if you apply L with your friend's invitation letter, you cannot tell the officer that you will do some business purpose in China and please insist your purpose to China is just for visiting your friend, otherwise, you may easily get rejected.