Abstract: Application of fire-resistant cables is becoming more and more widespread,but there are many factors that affect the internal temperature field during combustion,making it difficult to analyze by conventional methods.For commercial medium-voltage fire-resistant cable (N-YJV62-8.7/15 kV),fire dynamics software FDS was used to explore the influences of ambient temperature,thickness of fire-resistant layer,and thermal conductivity of fireresistant layer on the temperature of conductor and insulation layer for medium-voltage fire-resistant cable during combustion,and then temperature field relationship between heat source section and non-heat source section inside the cable was discussed.Results showed that conducting combustion tests at different ambient temperatures had a relatively small impact on internal temperature of the cable.In cables,an incease in the thickness of the fireresistant layer could result in a lower temperature of conductor and insulation layer;similarly,a decrease in thermal conductivity of fire-resistant layer could also lead to a reduction in the temperature of conductor and insulation layer.Meanwhile,temperatures of each layer in the heat source section of cable were significantly higher than those in non-heat source section.As a result,FDS simulation technology has high accuracy in combustion simulation of medium-voltage fire-resistant cables and also has guiding significance for the structural design of medium-voltage fire-resistant cables.