Abstract: The paper introduced the structure and principle of DTH hammer drilling with concentric simultaneous casing,which used in seismic exploration drill in gravel.In view of the problems such as low intensity,short lifespan of casing thread and the impact face of inner bit and outer bid in using process,the intensity of the accessories is analyzed with finite element technique.The paper proposed the methods of developing lifespan of casing thread and inner bit and outer bit.