Abstract: With ammonia and boron modified phenolic resin as matrix material and basalt fiber as reinforcing material,three kinds of ablation-resistant composites is prepared.The mechanical properties and ablation performance tests of the composites are conducted.It is found that basalt fiber reinforced boron modified phenolic resin has optimal mechanical properties and ablation resistant performance.Based on SEM analysis of surface topography and EDS analysis of surface adhesion material,ablation mechanism of phenolic resin-based composite is discussed.