The gating system is usually made up of the sprue, the runner, the gate and the slag well. It is an important component of the mold. On the basis of relationship among runner’s geometry, the pressure fall of plastic melt flowing in runner, flow rate and material properties, we can use the UDF library features and Pro / Toolkit functions in PRO / E software to do the second development of PRO / E software. As a result, we can establish the CAD module of gating system for the injection mold. The module has the perfect function and good generality and can help the designer for cost reduction. It may be used whenever you want to use. The PRO / E software has a powerful function to design mold. Taking these as a base, it is very convenient for the module to design the gating system of injection mold.