(The real name of this song is Chen Yue's "Luan Hong", I guess...)

It's a flute, a bamboo flute. The clear and beautiful one is the Qudi. This piece is played on the flute in the key of C.

The flute is relatively low-pitched and has an ethereal and long sound, while the sound of the flute is a bit dull in my opinion>.<. . .

The difference between the three is quite big. You can search and compare their sounds~