Geological drilling engineering is a complicated system engineering and design of diamond bits is a complicated system. Russian Doctor of technical sciences and Professor Skoromnyh V.V. and others have designed surface set diamond drill bits using the system theory approach, where the mechanical penetration rate is taken as the objective function with the cutting depth of the drill bit as a cut-in point to build the mathematical model, and develop the program to perform computer modeling. The modeling results allow the working situation of the diamonds in the bottom hole and rock fragmentation process to be seen more directly, which have some practical significance for in-depth research on the mechanism of rock fragmentation process and assessment of the rationality of the diamond bit design, and their influence on the technical and economical index of drilling.