Abstract: The factors affecting the rotation speed of cone are very complex during the drilling,therefore,the study about ratio of velocity between cone and bit plays an important guiding role to the rock breaking mechanism and bit design.The modeling theory of ratio of velocity between cone and bit such as torque balance and minimum work,and its advantage and disadvantage have been summed up in this paper.Based on the analysis of staging testing results,the main factors affecting the ratio of velocity between cone and bit include:structural parameters of bit,weight on bit (WOB) and rock hardness.Based on the above research,it is assumed that the cone structure is symmetrical and the cone axis is the central major axis of inertia.Under the assumption,a new simulation model about ratio of velocity between cone and bit based on law of rotation has been created,taking into account the main factors such as the structural parameters of the bit,WOB,and rock hardness.By using mathematical regression method for processing the test result,the correlation coefficient of the simulation model built has been obtained.Based on comparative analysis,the result has been achieved that the error between the calculation result of simulation model and the actual test result is small.So,the built simulation model can be used to calculate the ratio of velocity between cone and bit and to lay a foundation for the analysis of cone bit rock breaking mechanism and the establishment of a drilling simulation model.