The presentation will introduce the transition project that the whole department of +150 SAS programmers has completely moved from SAS to Open-source programming. The whole department switched from SAS Studio to R Pro Server, Window server to AWS Cloud computing environment, and the transition of SAS programmers to R/Python programmers. The presentation will also discuss the challenges of the project such as inexperience in Open-source Programming, new analytic platform, and change management. It will introduce how the transition-support team, executive leadership and SAS programmers have overcome the challenges together during the transition. It will also discuss the difference in SAS and Open-source language and programming, and it will show some examples of the conversion of SAS codes to R/Python codes. Finally, it will close with the benefits of the Open-source programming culture and the lessons learned from the transition from SAS to Open-source programming.