With　the　rapid　development　of　underground　space,　the　issue　of　safety　in　construction　processes　is　becoming　more　and　more　significant.　The　purpose　of　this　paper　is　to　solve　the　problem　of　the　existing　underground　space　monitoring　technology　not　being　centralized　and　unified.　In　view　of　the　problems　related　to　large　underground　spaces　in　the　process　of　constructing　complex　structures,　with　the　introduction　of　Internet　of　Things　technology　and　digital　twins,　we　put　forward　an　application　of　an　intelligent　safety-monitoring　digital　twin　system　in　the　construction　of　a　large　underground　space　structure,　and　at　the　same　time,　explore　the　Internet　and　digital　integration　mechanism　of　the　twin　system.　The　twin　system　uses　BIM　technology　to　establish　the　corresponding　physical　construction　model,　and　collects　multi-source　heterogeneous　monitoring　data　in　real　time　through　Internet　of　Things　technology　to　achieve　the　exchange　of　information　between　the　virtual　construction　model　and　the　physical　construction　model.　The　twin　system　uses　the　multi-source　heterogeneous　data　for　real-time　security　analysis,　and　obtains　the　security　status　of　the　structure　and　feeds　it　back　to　the　application　service　layer.　The　effectiveness　and　practicability　of　the　twin　system　in　large　underground　spaces　are　verified　by　an　example　project.　Aiming　at　the　safe　performance　of　the　orthogonal　arch,　the　mapping　relationship　of　various　parameter　indexes　is　obtained,　and　reasonable　control　measures　are　given.　This　study　provides　a　new　solution　for　improving　the　safety　of　construction　projects　and　risk　prevention　and　control,　and　has　important　theoretical　and　practical　value　for　the　safety　management　of　underground　space　construction　processes.