I am canadian citizen, coming to HK for business for a week.

You can try by land from HK to China mainland. Cross-border buses are frequent between HK and Guangzhou or Shenzhen. You can even choose to use local metro trains from HK to Shenzhen easily.

For traveling mainland China, you need to have a single entry Tourist L. For applying L type, you need to prepare your valid passport, an application form with a recen taken photo, round trip flight tickets and hotel bookings to apply at your local nearby CVASC.