The invention discloses a regenerated PA6 (polyamide 6)-base flame-retardant electric-insulating heat-conducting composite material, and a preparation method and application thereof. The regenerated PA6-base flame-retardant electric-insulating heat-conducting composite material is composed of the following components in percentage by weight: 18-50% of regenerated PA6 resin, 40-70% of electric-insulating heat-conducting agents, 1-10% of nitrogen flame retardant, 0.1-0.5% of anti-dripping agent, 1-6% of whitener, 0.5-2.0% of surface treatment modifier, 0.1-0.8% of antioxidant and 0.2-1.0% of lubricant. By compounding the regenerated PA6 resin, common electric-insulating heat-conducting agent and high-efficiency electric-insulating heat-conducting agent and adding the nitrogen flame retardant according to the preferable formula, the electric-insulating heat-conducting agents are subjected to a coating-single screw extrusion-double screw extrusion continuous production technique by the high-speed mixer, so that the prepared composite material has the characteristics of favorable flame retardancy, high heat conductivity, favorable electric insulativity, low density, low cost, favorable processibility and the like.