Hello. From Harbin airport to Yabuli, can I buy bus ticket to Yabuli online? What is the website?

The airport does not provide the shuttle bus to Yabuli, so if you want to take the direct bus, you may need to ask the Yabuli Resort to see whether they provide the pick-up service.
If they provide such kind of service, you may book the bus ticket from them and I think they will tell you how to do that.