Study the existing advancing mechanism of drill, analyze the disadvantage of the flat key and the spline, and the feature of the three circular arc equidistant profile connection. Taking the common chain advancing mechanism as basis, using three circular arc equidistant curve to make sprocket bore and intermediate shaft external cylindrical fit constitute the three circular arc equidistant profile keyless connection. Then introduce the advancing mechanism with three circular arc equidistant profile connection of drill. Applying Solidworks2010, we created the three-dimensional modeling of the mechanism, which lay the foundation for the further research and application. The new type advancing mechanism has many advantages, such as automatic-centering accurately, convenient in assembling and disassembling, eliminating the stress concentration, simplicity of the fit section，transferring bigger torque, suitable for heavy-loaded rock drill machine.