There is direct flight between Chongqing and Siem Reap,every five days. It departs at 10:00 from Siem Reap and arrives in Chongqing at 14:30 Beijing Time, while departs 15:30 from Chongqing and reaches Siem Reap at 18:00 at local time. The flight is runned by Angkor Airways Corporation. You can enquire the office for more detailed information. Good Luck！