I'm from Singapore. What is the harbin airport? from Shenyang to Harbin, is it convenient?

It is no need to go to the airport. There are high speed trains avaiable between these two cities. The train ride only takes about 2.5 hours. As for the attrations, you are recommended to visit Shenyang Imperial Palace, Zhaoling Tomb, Fuling Tomb, Qipanshan Scenic Area, Liaoning Provincial Museum, etc.