Direct flight

Yes. You can directly check Turkish Airline
http://www.thy.com/en-INT/index.aspx.
You need to book online.
For example, on April 9, departure HK at 23.05pm and arrive Istanbul on April 10 at 6.05am. Totally 12 hours, non-stop.
The flight fare is Euro 748.25 for round ticket.

2009-03-02 12:43:11 補充：
There is few of travel agent handling Turkish Airline. Hence normally they need to have one stop. If you would like to direct flight, then you must book Turkish Airline because Istanbul is the city of Turkey. They must have direct flight to Hong Kong.

我問過也是沒有, 至少都要停一次, 中東或歐洲
Emirates 最便宜
其次是Qatar
不然就是Air France, Lufthansa, KLM
價錢差不多
看你喜歡在那個機場等