The invention relates to a heat-insulating coating material for preventing a hot-end component of an automobile engine, and a preparation method thereof, belonging to the technical field of heat-insulating preventive materials. By selecting high-purity metal and alloy including ferrum, chromium, molybdenum, carbon, silicon, erbium, ferro-boron and the like, the alloy powder with the particle size of 20-43mum can be finally prepared by adopting a high-pressure Ar gas atomization method, the alloy powder comprises the following components in percentage by weight: 5-20% of Cr, 15-30% of Mo, 1-4% of C, 0.5-3% of B, 0.5-2.5% of Si, 0.5-3% of Er, and the balance of Fe and inevitable impurities. A Ferrum-based non-crystal heat-insulating coating is prepared by adopting a hypersonic flame spraying technology, and the prepared coating has relatively lower heat conductivity, and can be used for preventing the hot-end component of the automobile engine.