trip.com (their international site) and ctrip.com (Chinese site) is a reputable online travel agent and probably one of the few online travel agents I would consider using over booking air travel directly with an airline, especially as many of the Chinese airlines have barely functional websites (their main market to sell tickets are mini apps within WeChat and Alipay and their websites are not a major source of business).
If there is a need to follow up later they have decent customer service in both Chinese and English and are usually clueful.
In so far as you're going to have to give over your identity information to book air travel, and for Chinese airlines that means giving your passport info at time of booking, then trip.com poses no significant risk.
If you have a few mins to further ponder there's actually a recent thread over in the China forum about trip/ctrip.com
The Ctrip/Trip.com GBU thread