Abstract: In order to analyze influence of air gaps or impurities in insulation layer on temperature rise of windings of mine-used flameproof dry-type transformer, a mine-used 1 000 kVA/10 kV dry-type transformer with continuous winding was selected as research object, inter-turn and inter-layer insulation structures of windings of dry-type transformer were introduced. Infrared thermal imaging camera was used for analogy analysis of temperature rise characteristics of the samples under different discharge types and different aging temperatures, and relationship between temperature and inter-turn discharge and inter-layer discharge of dry-type transformer using Nomex insulation paper as insulating layer was obtained. Using theory of heat transfer and combining with insulation material characteristics to calculate and analyze the influence of inter-turn discharge dry-type transformer on heating process of windings. The paper provides theoretical basis for accurately locating hot spot temperature inside transformer and partial discharge point.