VBA as the environment of develop software can share the data with other program, this makes connecting and processing more easyily. Using VBA which is embedded in Auto CAD, this paper developed the software for the automatic design of drip irrigation. With this program the users can finish the design work easily. This software contains three modules, knowledge module, calculating module and document module. Through these facilities, the users can finish the work of design. It produces the Excel to transmit the data, which is necessary for the design and choosing equipments. Further more the software provides the ports for exchanging information.