Background. The article is devoted to the study of the scientific works of Sang Tong in the field of the national theory of harmony. His studies has a leading role in the development theoretical thought in the area of Chinese musicology and composition. Sang Tong’s contribution to national music education is determined by clarity of presentation of his teaching materials supported by numerous examples that is motivation for students to comprehend the science of composition. Being an outstanding composer, Sang Tong talentedly integrated the dissonant and pentatonic writing, emphasizing in his writings the national specifics due to atonal organization of music. The works of Sang Tong sounds abroad, they are performed on a concert stage, occupies a worthy place in the educational process of students of conservatories from different countries. In this connection, seems to be relevant the purpose of this article is to identify the main provisions of the theoretical works of the outstanding Chinese composer in the field of the national science of harmony and their role in the development of Chinese musical art in the second half of the 20th century. The mastering of this information is extremely necessary for the performers of San Tong music, as well as for teachers who are studying this musical repertoire in a class with students. Finally, the information presented will provide an opportunity to comprehend the artistic value of the musical heritage of Sang Tong, as well as allow attract more wide circles of professional musicians and audiences to his works. The results of the study. The first theoretical work of Sang Tong was the article “Theory of chord application and their subordination” (1957), where the musician analyzes the views of various authors on the problem of harmonization in composer’s work, systematizes them, giving a personal assessment. He gives many examples of the use of one or another composition tool. The composer considers methods of textural complexity in the study “Parallels to historical evolution and its application in Chinese and foreign musical works combined with pentatonic melody” (1963). In searching for his own composer’s writing, Sang Tong wanted to find the perfect textural balance: on the one hand, not reaching the difficult to perceive linear polyphony, on the other – not simplifying the texture into primitive forms of contrasting polyphony (as a variation of heterophony). The research experience of the 1960s and the 70s Sang Tong summarized in the monograph “Discussion on the horizontal and acoustic structure of pentatonic” (1980), which became a quality-teaching tool in the field of secondary music education. University vocalists also study at lectures on harmony, which helps them to expand the horizons of knowledge about national music. In 1982, Sang Tong published the first comprehensive study of contemporary music in China entitled “Introduction to harmonic processing techniques” in the journal Musical Art. Since 1994, Sang Tong planned to write a fundamental work that sums up his research – the ontology of Chinese music, but from year to year, because of illness, postponed it. Finally, in 2004, the Shanghai Music Publishing House published a series of Sang Tong articles in the form of a monograph “The Historical Evolution of Semitones”. This work is a fundamental study of the history of the development of harmony in China, which provides answers to the questions of the evolution of Chinese semantics and, related to it, the theory of the acoustics of Chinese instruments. Thinking about the quality of secondary music education, Sang Tong decided to prepare a textbook for an initial five-year program of study. In 2001, he published the Harmony Course, submitting it to the state commission for consideration as a school textbook. The San Tong’s Course of Harmony has become a basic national textbook in China. To date, the level of this theoretical work is considered unsurpassed and attributed to masterpieces in the field of music education. It is distinguished by a solid theoretical foundation that allows the students to find any answers to questions concerning the principles of voce-leading, transport, rules of resolution of various intervals. Conclusions. The composer and theorist Sang Tong entered the history of Chinese music of the twentieth century as the founder in the field of the modern national theory of harmony. For more than fifty years of academic research, Sang Tong has made an outstanding contribution to the development of theory of harmony in China, was creating a number of musicological studies of harmony that demonstrate the highest theoretical level. He laid a solid foundation for the future development of the national school of harmony theory, bringing the younger generation of Chinese composers to a high professional level.