The monograph discusses topical issues of sustainable development of mutually beneficial cooperation between the three countries in the context of the implementation of the Mongolia-Russia-China Economic Corridor Program, adopted in 2016 at the highest political level. The most important global task for Mongolia is to ensure favorable conditions for the formation and development of such a corridor, as well as the construction of a main gas pipeline from Russia to China via Mongolia.Particular attention is paid to the prerequisites and conditions for creating the economic corridor, as well as the formation of the necessary institutions and mechanisms for mobilizing domestic resources to turn the economic corridor into an effective lever of development of the three countries. Specific conclusions are made, on the basis of which the author proposes a new concept of development of the transport corridor "Mongolia - Russia - China" in modern conditions.