If I fly from Taipei to Xiamen and transfer to Haikou on the same day, do I need to be quarantined in Xiamen without leaving the airport?

Unable to transfer, it will take several hours for quarantine sampling when entering Xiamen (including Hong Kong, Macao and Taiwan), and then sent to a designated isolation point for centralized medical observation for 14 days.

According to the current policy, you will be quarantined at the port of entry for 14 days on the day of entry.

Quarantine in Xiamen.