The article is devoted to the search for new methods of high-quality professional development of mathematics teachers in comprehensive schools. The following research methods were used: analysis of scientific literature on the problem under study, analysis of the content of the Unified National Testing tasks, reasons for low results of passing the UNT by school graduates, a pedagogical experiment in the secondary school named after K. Tokayev in Ushtobe, Karatal district, secondary school named after D. Kunayev in Saryozek urban-type settlement, and schools in Kerbulak district, Zhetysu region, the Republic of Kazakhstan. The study of the problem led to the definition of a contradiction between the broad classical training of students and their narrowly focused professional orientation. It was revealed that the academic load in a secondary comprehensive school is 40% less than the load in "status" schools - gymnasiums and lyceums, which have approximately the same volume. Conclusions were made that the developed methodology for advanced training will create conditions for the effective development of the readiness of subject teachers and educational organizations to use regulatory and educational and methodological resources that ensure high-quality performance of professional duties.