Based　on　the　then　high-tech　industry　policy　documents　issued　by　Beijing　in　2017,　this　paper　builds　a　complex　network　model　to　reflect　the　internal　structure　of　Beijing’s　High-Technology　Industry　Chain　(BHIC),　and　then　analyzes　the　coevolutionary　mechanisms　of　ten　top　high-technology　industries　and　their　detailed　sectors.　Especially　for　the　science　and　technology　service　(S&T)　industry,　this　paper　measures　its　function　and　status　in　the　system　and　studies　its　concrete　approach　to　stabilize　the　development　of　the　industry　chain.　Finally,　policy　suggestions　to　promote　the　development　of　the　S&T　service　industry　in　specialization,　networking,　and　scale　are　put　forward.　©　2023　by　the　authors.