This article studies the questions of military and economic aid to China in the early period of the Sino- Japanese War. On the example of archival documents the author consideres the position of the Soviet Union in full-scale war against China launched by the militarist Japan in July 7, 1937. The research objective was to show the special situation of Xinjiang province using document materials. In time of war this province played a very important strategic role, with a single trafic arterial, which linked the warring China and the Soviet Union passing through it. Besides, the author points out in the paper that Xinjiang was the only region, a kind of rear base, that could solve the important task of supplying the Chinese army with necessary materials in a short time. Also, the research points out that one of the main problems in the work of the thruway from the Soviet Union to China, was the delivery of fuel to fill up combat vehicles. This problem was solved by an oral agreement to set up a joint company for construction and exploitation of the Tushantszy oil refinery plant on a parity basis.