In 1999, the Republic of Belarus began to educate children with severe multiple disorders (SMD). For this purpose, new special educational institutions – correction and development training centres (CDTC) – were opened across the country. Curricula for preschoolers with SMD appeared only in 2011, and curricula approved by the Ministry of Education of the Republic of Belarus appeared in 2014. Before 2011, teachers were more engaged in the care and supervision of preschoolers with SMD than in the actual educational process. Currently, changes are taking place in preschool education. The education of children with SMD should be built on a competency basis where the formation of their life competencies should play the leading role. The need to assess the quality of such education has emerged, and, consequently, the issue of professional training of specialists of CDTC in this direction. The aim of the article is to determine the possibilities of the system of professional development of teachers of specialized institutions on the issues of quality assessment of education of pupils with severe multiple disorders at the present stage in the Republic of Belarus. The basic methods in the study of this problem were questioning and content analysis. The experimental base of the study is represented by 63 state educational institutions “Centre for Corrective and Developmental Education” (Brest, Vitebsk, Gomel, Grodno, Mogilev, Minsk regions and the city of Minsk, Republic of Belarus), as well as 8 institutions providing professional development of CDTC personnel (Brest, Vitebsk, Gomel, Grodno, Minsk regions, the city of Minsk, Republic of Belarus). The study involved 345 respondents: 334 teachers of CDTC and 11 employees of professional development institutions. The study was conducted in 2020. The article presents the author’s view on assessing the quality of education of preschool children with SMD, highlights the results of the empirical study, and substantiates the possibility of changing the training of teachers of CDTC in the context of professional development institutions. The obtained data allow us to see a holistic picture of the modern system of professional development for special teachers on the problems of assessing the quality of education of preschool children with SMD, which further allows to adjust the training programs of professional development in specialized institutions (Academy of Postgraduate Education, Institutes of Education Development), to include the most popular topics in their content.