The characteristics of pipe network for drip irrigation system are analyzed. A computer model for the design of pipeline drip irrigation system is presented. Based on the extended application of AutoCAD software, a new numerical method, namely PIPE algorithm, is introduced, which contains translocation, intersection, attribute data operation, and other basic features. Using the model and the PIPE algorithm, various forms of pipe network can be set rapidly. The results demonstrate that the model is effective, and can be used to direct developing of computer-aided software for other irrigation system.