There are many BGMs in "Know whether they should be green, fat, red and thin", among which the more out-of-the-box ones are:

1. The theme song "Know whether you know" is composed by young people Composer and music producer Liu Xuandou composed the music, musician Zhang Jingyi and Song Dynasty female lyricist Li Qingzhao collaborated on lyrics across ancient and modern times, musicians Liu Jing and Yang Yu supervised the production, and Hu Xia and Yu Kewei were invited to perform a passionate duet.

2. The interlude "Concern" was written and composed by Li Zongsheng and sung by Hu Xia.

3. The interlude "Reluctant to Leave" was written and composed by Li Zongsheng and sung by Hu Xia.