The article presents and theoretically substantiates the criterias, indicators and levels of preparedness of primary school teachers for integrated learning as one of the leading innovative activities on the modernization of the educational system in Ukraine, analyzes different approaches to determining the components and criterias of teachers' readiness for various aspects of activity in the research of domestic and foreign scientists. Based on the analysis, the author states that there is no single approach to determining the criterias of teachers' readiness for professional activity and the tendency of most scholars to choose criterias from the point of view of motivational, personal, cognitive, activity, and reflective structural components. Due to this connection, it is proposed to distinguish axiological-motivational, personality-creative, cognitive-epistemological, operationalactivity and reflexive-evaluation criteria of the readiness of primary school teachers to integrate learning and to characterize their indicators, to identify and adapt their indicators, heuristic-search, and creative-productive levels of professional readiness. The obtained scientific results are organized into a single table "The Criterias, indicators and levels of readiness of primary school teachers for integrated learning", which visualizes the findings of the study and focuses on the certain logic of the proposed components. The author has been provided the prospect of further scientific researches in the creation of diagnostic methods for the effective evaluation of indicators of professional readiness and organization of pedagogical experiment for their implementation in the practice of postgraduate pedagogical education.