The implementation of any type of joint or combined operation is in the form of combat systems, it is a successful operation that has strong systems and is under the guidance and direction of a commander. Therefore, the condition of success in any war depends on the role of war systems and how to follow the principles of war. It seems that combat systems did not play an acceptable role in this war, therefore the main goal of this article is to explain the role of combat systems in the Russian-Ukrainian war. This article is practical and implemented in a contextual-case method, the information and data tools are library and field, the sample size is 54 people. According to the findings of the research, one of the reasons for the erosion of the war was the functional weakness of the nine combat systems and the lack of optimal use of naval power, especially on the Russian side. According to the results of the research, the Russian missile and combat engineering system has performed well, while the Ukrainian defense system has had a successful performance in shooting down Russian drones, the rest of the systems have not performed successfully during the war. Of course, at the beginning of the war, Russia's operation, artillery, air and defense system worked well, but during the war, due to the support of the United States and NATO to Ukraine, the superiority and advantages of the Russian army were somewhat neutralized by Ukraine.