“Gray customs system” is an illegal practice of getting goods across the border without official customs approval. Such practice makes a negative impact on Russia-China economic relations and is, therefore, considered as a barrier for bilateral economic relations between Russia and China. In this context, the paper examines the problems occurred due to the gray customs system and the action taken to mitigate this problem. The research method used for this article is the case study method referring to secondary data, scholarly literature and reports.