Through the principles of building the lesson process, the steps of designing multimedia lessons in teaching theoretical lessons of Defense and Security Education for students at T.ĐĐL as well as some illustrative lesson designs let us know what is necessary. How to design a multimedia lesson in the subject of Defense and Security Education so that teachers can design and teach multimedia. To design multimedia lessons requires teachers to adhere to the principles of building teaching processes, steps to design multimedia lessons as well as prepare and arrange all knowledge in the most reasonable way. knowledge from basic to advanced, as well as expanded to include in lessons, thereby helping students absorb the most amount of knowledge in the most vivid and easy-to-understand way. And depending on the content of the lesson, depending on the teacher’s sense of implementation, each person and each lesson will have their own way of implementation but still follow the principles and basic design steps above.