Abstract: Soft rock support in underground coal mines has always been the key problem that restricts the productivity and affects the safety of mining excavation. At present, domestic coal mines mainly use the combined support with anchor shotcrete and steel arch. Because the traditional anchor shotcrete support is passive support, the support structure can not play a supporting role quickly in the early stage of support, which leads to the formation of large unloading deformation of broken surrounding rock. In order to increase the initial support force, improve the integrity of fractured coal rock mass, and reduce the unloading deformation of surrounding rock mass, this paper adopts adaptive steel arch structure with anchor system to support fractured coal rock mass. Taking the soft rock roadway of Changcun Coal mine as the engineering background, the supporting mechanism of the adaptive steel arch is studied by numerical calculation, and the supporting effect of the adaptive steel arch is quantitatively analyzed by comparing with the deformation, stress and internal force of the surrounding rock of the unsupported and conventional steel arch anchor shotcrete support. This paper verifies the research results according to the in-situ support effect and monitoring of rock mass deformation.