A 100 mm diameter split Hopkinson pressure bar(SHPB) apparatus, coordinating with electric furnaces, was adopted to investigate the behavior of concrete at room temperature, at and after exposure to 200, 400, 600 and 800℃ under impact compressive loading, the effects of high temperature and projectile velocity on impact mechanical properties were studied. Results show that the effect of high temperature on impact mechanical properties is significant. The critical temperatures for significant change of mechanical properties of concrete at and after exposure to high temperature are 600℃, 400℃, above these temperatures, dynamic compressive strength and specific energy absorption of concrete decrease rapidly. For concrete exposed to high temperature of above 400℃, cooling down by water results in serious strength reduction, which should be paid attention in fire fighting. Though the loss in strength of concrete at above 400℃ is severe, it still shows a nice anti impact toughness under higher velocity impact loading. Above all, concrete is an excellent thermal resistant and anti impact material, which is very important to military defensive engineering structure.