Abstract: In this paper,the course of knowing the underground space structure and its support characters is summarized;relation between bolting shotcrete support and NATM(New Autrian Tunneling Method)is discussed through systematic analysis of origin,development and essence of the NATM method in combination with deformation failure characters of coal mine's soft rock drifts;some problems in explaining the mechanism of bolting shortcrete support by NATM basic principle are described.