Combinatorial analysis of the German sonnet corpus based on mathematical study of verse was carried out on poetic works by Rainer Maria Rilke. Sonnets rhyming methods classification based on their symmetry relations in quatrain and tercet parts was constructed. According to this classification, which does not take into consideration the so-called irregular sonnets, the concepts of symmetric, partially symmetric and asymmetrical sonnets are introduced and the possible quantity of sonnets of each type is calculated by means of the combinatorial method. Taking into account these notions, the unique combinatorial potential of the poet has been revealed, and the evolution of Rilke’s sonnets structure from “New poems” (“Neue Gedichte”) to “Sonnets to Orpheus” (“Sonette an Orpheus”) is also investigated. The notions of symmetrical and independent sonnets are introduced. Using these notions, it is shown that “New poems” contain just independent sonnets, which have non-recurring rhyming variants, while in “Sonnets to