This paper attempts to explain the factors for Russia to carry out Military Interventions in Syria during 2015-2018. Syria is one of the countries in the Middle East that experiences unstable politics because the Syrian people demand President Bashar Al-Assad to retire. Russia as a long-time ally of Syria was involved in the conflict. This caused various questions to arise regarding Russia's involvement in the conflict in Syria. This paper uses the concept of Military Intervention and the concept of National Interest to answer the factors of Russian Military Intervention in civil conflict in Syria. The method used in this paper is qualitative research methods. The author concludes that Russian military intervention in Syria during 2015-2018 was to protect Russian military bases in both Latakia and Tartus. Russia also wants to increase arms sales in Syria and the International Market.