Authors structure the theory of comparative vocational education study; determine the theory’s prerequisites, core and consequences. The theory prerequisites are presented in terms of VUCA-world, globalization and deglobalization, due to the variety of developed comparative studies approaches. The core of the theory is an ontological model based on the principle of transdisciplinarity, contextual and communicative approaches, method of the "network" and fractal matrix tables method. They as well have their qualitative, quantitative and interpretative methods and includ educational transfer as the main mechanism and term for the best educational practices export. The consequences of the theory are originated from the ontological model that actualizes the predictive function of comparative studies, and consist in the possibility of generating derived ontologies based on the forecast graph, their new levels, sublevels and connections between them, modeling transfer practices and changes in the system that accepts transfer, foreseeing and the emergence of new phenomena of education.