Non-Pharmaceutical　Interventions　(NPIs)　have　been　widely　employed　globally　over　the　past　three　years　to　control　the　rapid　spread　of　coronavirus　disease　2019　(COVID-19).　These　measures　have　imposed　restrictions　on　urban　residents＇　activities　and　significantly　influenced　sewage　discharge　characteristics　within　sewage　network,　particularly　in　densely　populated　cities　in　China.　This　study　focused　on　the　nodal　flow　diurnal　patterns　and　sewage　network　operational　risks　before　and　after　epidemic　lockdown　in　Beijing　from　March　to　May　in　2022.　Nodal　flow　diurnal　patterns　on　weekdays　and　weekends　before　and　after　NPIs　were　analyzed　using　measured　data　through　statistical　and　mathematical　methods.　A　sewage　network　model　was　established　to　simulate　and　analyze　the　operational　risks　based　on　InfoWorks　ICM　before　and　after　epidemic　lockdown.　The　main　conclusions　were　as　follows:　(1)　In　predominantly　residential　areas,　the　total　wastewater　volume　increased　by　approximately　28.76　%　to　33.52　%　after　the　implementation　of　strict　NPIs.　The　morning　and　midday　＂M＂　peaks　on　normalized　weekdays　transformed　into　＂N＂　peaks,　and　the　morning　peak　time　was　delayed　by　0.5　to　1　hour　after　the　lockdown;　(2)　Following　NPIs,　More　than　90　%　of　manholes＇　average　water　levels　rose　to　varying　degrees,　approximately　50　%　of　pipe　lengths　exhibited　a　full　flow　state;　(3)　When　the　lockdown　was　in　place　during　a　hot　summer　day,　sewage　overflow　phenomena　were　observed　in　4.6　%　and　9.6　%　of　manholes,　respectively,　with　per　capita　daily　drainage　equivalent　reaching　40-50　%.　These　findings　hold　significant　implications　for　the　proactive　planning　and　operational　management　of　water　industry　infrastructure　during　major　emergencies.