BEIJING—China’s Ctrip.com has been helping Chinese tourists explore foreign lands for more than 15 years.

Now Ctrip itself is going overseas.

Ctrip.com International Ltd. , China’s largest travel website, said Wednesday that it is buying British counterpart Skyscanner Ltd. for £1.4 billion ($1.7 billion). It is the latest in a series of expansion moves by Ctrip, whose growth has paralleled that of China’s middle class and its appetite for travel.

The acquisition will allow Ctrip and Skyscanner to share technology and know-how, newly appointed Chief Executive Jie Sun told analysts on an earnings call Wednesday. For example, Skyscanner’s front-end search functions could be paired with Ctrip’s back-end booking software, Ms. Sun said.

“It will extend our air-ticketing business to a much bigger footprint in a global marketplace,” said Ms. Sun.