The relevance of the presented problems in the paper is conditioned by the fact that the process of implementation of the competence approach into the educational space of Russia is in contact with a number of theoretical inconsistencies which are directly related to understanding the formation and mastering of competences. The goal of the paper lies in justification of the structure of competence and psychological (tangent-integrative) mechanism for its formation that will allow to propose a structural-functional competence model of competence's formation in the process of learning. The leading method to study the defined problems is the method of analysis of critical incidents of professional activities of successful performers, as well as the modeling method, which allowed us to consider a scientific problem with the position of domestic systemically-active approach of individual trajectory of professional skills' formation in the learning process. Rank places are presented of basic definitions of competence-based approach, obtained in the results of research of the concept of "competence", the comparative characteristic is given of qualities included in the concept of competency and competence, psychological tangent-integrative mechanism is justified of competence's formation that made it possible to present the structural-functional model of competences, including the groups of professionally significant qualities that characterize the competency of a specialist. The structure of the competency and competences allows from the position of the activity approach to deepen knowledge about the nature and content of the competence approach and the structural-functional model allows us to consider the competence as psychological qualities' system, the back-bone of which is the intention, which opens up the wide field of activity for the justification of the key professional competences of education institutions' graduates.