what's the easiest way to get to Jiangkou,Putian, Fujian from Xiamen international Airport?

Well, there is no direct long-distance bus at the airport that can take you to the destination.
You need to take airport shuttle bus to Gaoqi Bus Station first.
Then take long-distance bus to Putian Bus Station. The bus schedules are 08:30, 10:00, 11:40, 13:20, 14:50 and 16:40. The ticket fare is CNY 65 per person.
After arriving, transfer a bus to Jiangkou directly. The departure times are from 06:05 to 18:30.