Abstract: When drilling hard formation or staggered formation,normal single layer flat base bit wears heavily.Therefore,we developed a new kind of directional drilling polycrystalline diamond composite(PDC) bit and analyzed its rock breaking mechanism and stress property by using numerical simulation method.Resultsshow that rock breaking load of the new bit decreases by 36% and breaking efficiency increases by 50% compared with normal bits at the same working condition. Field tests were implemented with the new kind of bits. It turns out that when drilling hard formation or staggered formation,the life of new bits is 3 times as much as that of normal bits,and that the drilling efficiency almost doubles. New kind of PDC bit could decrease the drilling cost.