Abstract: In response to the dual challenges of thermal management and fire safety, to overcome the negative interactions between boron nitride (BN) and intumescent flame retardant (IFR) and achieve the co-enhancement of thermal conductivity and flame retardancy, a stepwise blending process was adopted in this study. By utilizing the influences of polyolefin elastomer (POE) in phase structure, the spatial distribution of IFR and BN was effectively regulated. The composites with segregated structure of dispersed flame retardant phase and continuous thermal conductive phase presented the thermal conductivity 0.75 W·m⁻¹·K⁻¹ and the limiting oxygen index (LOI) of 28.3%, which were 17% and 33% higher than the traditional composites with dispersed structure, respectively. While reaching UL-94 V-0, the peak heat release rate (pHRR) and peak smoke release rate (pSPR) during combustion decreased both by 63%. The segregated structure was revealed to make significant contribution to simultaneous enhancement of flame retardancy and thermal conductivity.