In order to improve the rock breaking efficiency and service life of the large diameter drill hammer in hard formation， ABAQUS software was used to establish the simulation model of rock breaking with spherical teeth. The curves of crushing specific work， invasion depth， crushing range and stress influence range of φ18mm spherical teeth in the process of impact cutting rock breaking under different drilling parameters were compared and analyzed， and the drilling parameters and tooth layout were optimized. The analysis results show that when the weight on bit is 1.2kN and the impact energy is 30J， the crushing efficiency of the rock is higher， the displacement of the spherical teeth into the rock can reach 0.67mm， and the stress limit of the rock is divided， and the influence range of the stress is 43.4mm. Through the simulation of double-tooth impact cutting， the better ring distance and spacing were determined： the ring distance was 47.4mm， and the spacing was 43.4~51.4mm. Considering the wear of the spherical teeth， using the ring distance and spacing， the teeth of the 711mm large-diameter drill hammer were optimized.