The aim of this paper is to clarify the process of in-service teacher training system in Mongolia.The in-service teacher training system in Mongolia continues to undergo repeated changes after the social system transition. Under such circumstances, it was stipulated in Article 40, Paragraph 8 of the 2012 Education Law that teacher training should be conducted every five years regardless of the installation form. Based on this regulation, the Institute for Teacher Specialty Improvement was established in 2012, and basic training for all teachers has started in 2013.Although in-service teacher training has begun to be implemented, it is unclear whether there will be any influence from international organizations, including the selection of training teacher, the training period, and so on. Due to the lack of research on related materials, the actual situation will be clarified through interviews.