The purpose of the article is to present the Leningrad Military Library of the Workers’ and Peasants’ Red Army (now the Information Historical and Scientific Center – Military Historical Library of the General Staff of the Armed Forces of the Russian Federation) – the main scientific library of the People’s Commissariat for Military and Naval Affairs of the USSR – path of formation. The relevance of the topic is due to the significant role of military libraries in preserving historical memory as the most important area of ensuring national security and sustainable development of the Russian Federation. The methodological basis of the research contains principles of historicism, consistency, and objectivity. The methods used are source studies, comparative, biographical. Based on the analysis of the source base, most of which contained previously unpublished materials from the Russian State Military Archive, the main stages of the library development in 1921-1936 are established, its staff, main activities, sources and dynamics of replenishment investigated. Libraries of military educational institutions nationalized in the early years of Soviet power, personal libraries and some military libraries of the Russian Imperial Army that entered the library collections are exposed. The data about the library chiefs and their contribution into its work organization are added.