Ji Kang’s monograph on music aesthetics is:

Ji Kang composed four musical pieces: "Changqing", "Duanqing", "Changside" and "Duanside", which were Later generations collectively called it "Ji's Four Nongs", and Cai Yong's "Cai's Five Nongs" were collectively called "Nine Nongs". They were highly praised in the history of Chinese music. Emperor Yang of the Sui Dynasty chose to play "Nine Nongs" as his choice. One of the conditions for being a knight. In the Song Dynasty, Yang Zan searched for the four music scores among the people, and found more than ten kinds of music scores, which shows its wide spread. "Xuan Mo" and "The Wind into the Pine" are also said to be his works. "Xuan Mo" reflects the thoughts of Lao and Zhuang.

These works can be found in collections of scores published in the Ming Dynasty, but they are not necessarily original works.

His work on his musical thoughts, "On Soundless Sad Music", is my country's first music theory work. The book concentrates his thoughts on music aesthetics and still has high research value until now. In the article, he discussed issues such as music and emotions, creation and performance, performance and musical instruments, appreciation, appreciation and habits. Through repeated arguments between "Qin Ke" and "Higong Ye Master", he proposed the concept of "Soundless Sad Music". This is the earliest typical expression of the aesthetics of "self-discipline" in the history of Chinese music.

Many musical aesthetic issues mentioned in "Soundless Music Theory" have founding significance. Lu Xun once pointed out: "Ji Kang's papers are better than those of Ruan Ji, with novel ideas and often contradicting the ancient theories.

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