The article deals with Sergei Bortkiewicz form, structure and functional experiments on sonata cycle in Sonata for Violin and Piano op. 26. The date of creation of the work is clarified. The article provides an overview of the history of development of the sonata cycle genre invariant. Comprehensive analysis of the work by Bortkiewicz provides tracing influences of West-European and Russian composing traditions. Different approaches to the interpretation of the composer’s idea are presented, which allows to explain the specific construction of the cycle.