In modern educational system reform in Russia, there is a deepening contradiction between the required and real level of professional competence of teachers. One way to overcome this contradiction is the systematic professional development of the teaching staff implemented with the help of distance learning technologies (DLT). One of the means to ensure high quality of training is course evaluation by trainees. It allows for motivation and a high level of training, to understand the directions of the course modification. At the same time, teachers themselves are professional experts in training, and their assessment of the e-course may be more objective than that of the trainees of other professions. Additional vocational education is primarily characterized by a high degree of applied orientation to modern learning technologies. Such are the realities that changes, especially in digital technology in education, are changing rapidly. And it is so fast that, in fact, one person cannot be aware of the full range of directions in which they (the changes) are taking place. This problem can be solved using the DLT through systematic modification of the e-course. The object of the study in this paper is the process of teachers' training in the system of professional development of pedagogical staff using distance learning technologies. The subject of the study: the mechanism of optimization of e-learning distance learning courses used in the system of professional development of pedagogical staff. Research purpose: to identify mechanisms to optimize the effectiveness of e-courses to increase trainees' motivation, correlation of theory content with practice with the help of trainees themselves under conditions of synergetic approach [1]. Research objectives: a) to identify parameters for improving the effectiveness of e-courses; b) to develop a toolkit for improving the effectiveness of e-courses; c) to develop recommendations for improving the effectiveness of e-courses. The method used in the study is the analysis of pedagogical literature, Google-form-based questionnaire, synthesis, and generalization. The novelty of the study is related to the creation of conditions for modifying e-courses for teachers' professional development through the examination of the course by the teachers themselves. This article is written within the framework of the Russian Foundation for Basic Research project 19-29-14176 "Building a Fundamental Model of Digital Transformation of the General Education System Using a Digital Platform for Results-Based Education".