Before IG-XL 10.40, VBA is more of a scripting tool in IG-XL for test program development. As the test codes are growing larger, those Legacy Codes are hard to maintain or may become unreadable. It may take hard work to add a brand-new test code or refactor the whole test program. C# is now the new supporting language in IG-XL test program development after IGXL 10.40.10. Compared with VBA, C# is a powerful and versatile object-oriented programming language that has become an essential tool for software development on .NET platform, so we can use the features (inheritance, overriding, overloading…etc.) of OO programming in IG-XL test program development to let test codes more readable and structured. Design Pattern is another tool that is used to solve the problems of Object Generation and Integration when moving to object-oriented programming. In this paper, we will introduce some Design patterns that can be used in IG-XL test program development. Singleton Pattern could solve the object generation problem and reduce unnecessary memory usage. Adapted Pattern simplified the structure of each Test Method in IG-XL. The Factory Pattern the complex test items or large data to be more organized. The implementation of Design Pattern might let IG-XL program develop more efficiently and developing.