This study comprehensively examines Igor Vladimirovich Sposobin's harmony system, one of the most prominent examples of the theoretical models developed by Soviet music pedagogy in the 20th century, in its historical, pedagogical and cultural context. Sposobin (1900-1954) was a decisive figure in the institutionalisation of music theory education in the Soviet Union; the theoretical systems he developed became standard curricula not only in Soviet educational institutions but also in other socialist countries such as China. This article systematically analyses the basic principles on which Sposobin's theory is based, its relation to Soviet ideology, its pedagogical methods and how it was adapted in other countries through cultural transfer. Uchebnik Garmonii (Harmony Textbook), one of Sposobin's main works, was designed not only as a theoretical source, but also as a pedagogical tool reflecting the artistic understanding and Soviet ideology of the period. The book aims to systematise tonal harmony within the framework of diatonic-based and functional categories, while gradually developing the student's harmonic thinking skills. This system is a simplified and localised version of Western European approaches to harmony - especially Riemann's functional harmony - combined with a disciplinary approach typical of Soviet pedagogy. In particular, the identification of each chord by both degree and function (e.g. T, S, D) is noteworthy as a pedagogical tool aimed at providing the student with not only a theoretical but also an intuitive sense of tone.

The article points out that Sposobin's system carries not only a pedagogical but also an ideological discourse. In line with the principles of socialist realism, which became evident during the Stalin era, art was moved away from individualistic and formalist conceptions and towards a populist, simple, functional and comprehensible line. This ideological framework is clearly felt in Sposobin's works. The teaching of harmony is positioned not only as the transfer of technical knowledge, but also as a tool for the upbringing of the socialist individual. The fact that the musical examples used are mostly chosen from Russian folk songs or classical Russian repertoire supports this ideological orientation. Sposobin's theory was also widely adopted in China from the 1950s onwards, and the work Uchebnik Garmonii was first translated into Chinese chapter by chapter, then completely, and became a compulsory textbook in Chinese conservatories. This process should be considered not only as an educational process, but also as a cultural and ideological transfer process. In China, the Soviet model of music education was adopted as part of the socialist construction process; diplomatic and cultural relations with the Soviet Union served as a legitimising function. The content of the book has been localised and reorganised to allow the harmonisation of traditional pentatonic structures specific to China. In this respect, the Sposobin system also functioned as a cultural model at the international level. The article emphasises that Sposobin's system offers a very strong pedagogical structure; however, it also has some limitations in terms of contemporary music education. The most criticised aspect of the system is that it centres on an overly normative and ‘one-truth’ approach. The student's space for developing creative solutions is limited; harmonic rules are often presented as inflexible structures. This has led to the inadequacy of this system, especially in post-20th century music - in areas such as modal harmony, jazz, serialism and post-tonal music. Moreover, due to its historical origin, the system has a certain ideological burden, which poses a problem for contemporary educators. On the other hand, the influence of Sposobin's theory on contemporary harmony education still persists. Today, many music schools and conservatories, especially in Russia and China, use direct or derivative forms of this system. Some institutions have hybridised this system with modern theoretical approaches (e.g. Schenker analysis, neo-Riemannian analysis, jazz theory, etc.) to develop more flexible and multi-layered teaching models. Thus, while benefiting from Sposobin's pedagogical discipline, more flexible analysis methods suitable for the diversity of the repertoire were also integrated into the system. In conclusion, this study shows that Igor Sposobin's harmony system functioned as a lasting and influential music theory not only during the Soviet Union but also on a global scale. Considering the historical context, pedagogical structure and forms of cultural transmission of the theory, it becomes clear that this system is not only a theory, but also an educational policy and cultural discourse. Sposobin's theory provides a powerful example of how the idea of functional harmony can be transformed as a pedagogical tool; it also reveals how music theory is intertwined with ideology, culture and teaching models.