This paper introduces a new kind of diamond bit body material. The characteristics of this material are as follows: the outer bit body cast with tungsten-carbide and the inside is steel shot. So the bit body has got high wear resistance on the outside and good mechanical properties inside at the same time. The mechanical properties inside and the wear resistance outside of the bit were tested. The paper also introduces how to apply a film of mixture of glue-included tungsten-carbide on the surface of the bit mold and graphite stick. The improvements of mechanical properties inside and maintenance of wear resistance outside have made much choice to design wider and deeper junk slots. Thus the performance of bit has been improved.