Abstract：For the research of the rate of penetration (ROP) prediction，the empirical or semiempirical equations of the ROP are derived from the laboratory or field data before. Some of them include some coefficients difficult to get，while some of them are not coincident with the field data. Based on the theory of the roller cone bit，the simulation model of the hammer bit drilling system is established，which includes dynamical model of the impactor，simulation model of the hammer bit，simulation model of the true bottom hole plane and the mathematical model between the tooth and the rock，by which the simulation software is developed. Hence the impacting force，the impacting work of the piston and ROP of the air hammer bit drilling can be predicted. Simulation results are coincident with that of the field so as to indicate that the model are reliable. The research can help to redesign the hammer bit or the impactor and select the drilling parameters.
