With frequent occurrence of all kinds of terrorism attack around the world,engineers begin to realize that improvement of antiblast of structural members can effectively prevent structure from integral collapse under blast loading and spare more time for people to escape.Studies are made of the mechanical performance of three simple supported RCBeams with fewstirrups under blast loading through experiments and analyses are made of their crack development,strain and deflection change.Results show that the beams begin to fail from the weak part and their antiblast can be effectly enhanced by increasing strength of concrete,enlarging Stirrup Ratio,and especially by reducing stirrup spacing of the two bottoms.