Conceptual scheme design software was developed by Visual C++ and Oracle to determine the conceptual design scheme quickly. This method can well memorize the past experience of designers. First, the layout and structure format of the landing gear for large-scale civil airplanes in existence was collected. Furthermore, the example databases for the damping and retracting system of large-scale civil airplanes were given. Finally, the design parameters of the conceptual design scheme were studied with the knowledge database. As a result, the software is satisfied needs of customers and realized the purpose of improving the design quality of the airplane and landing gear, and shortening the developing time.