From HK to Qinhuangdao, are there flight? If there are no direct flights between, which method is the fastest one?

I'm afraid there is no direct flight. I suggest you take a plane to Beijing first. At Beijing Capital Airport, you can take the direct long-distance bus to your destination. Buses for the journey are scheduled from 09:00~18:00 hourly, 19:30, 21:00 and it takes about 4h. Thre bus fare is CNY140 per person.