Exploring　the　relative　role　of　different　indoor　environments　in　respiratory　infections　transmission　remains　unclear,　which　is　crucial　for　developing　targeted　nonpharmaceutical　interventions.　In　this　study,　a　total　of　2,583,441　influenza-like　illness　cases　tested　from　2010　to　2017　in　China　were　identified.　An　agent-based　model　was　built　and　calibrated　with　the　surveillance　data,　to　assess　the　roles　of　3　age　groups　(children　＜19　years,　younger　adults　19-60　years,　older　adults　＞60　years)　and　4　types　of　indoor　environments　(home,　schools,　workplaces,　and　community　areas)　in　influenza　transmission　by　province　with　varying　urbanization　rates.　When　the　urbanization　rates　increased　from　35%　to　90%,　the　proportion　of　children　aged　＜19　years　among　influenza　cases　decreased　from　76%　to　45%.　Additionally,　we　estimated　that　infections　originating　from　children　decreased　from　95.1%　(95%　confidence　interval　(CI):　92.7,　97.5)　to　59.3%　(95%　CI:　49.8,　68.7).　Influenza　transmission　in　schools　decreased　from　80.4%　(95%　CI:　76.5,　84.3)　to　36.6%　(95%　CI:　20.6,　52.5),　while　transmission　in　the　community　increased　from　2.4%　(95%　CI:　1.9,　2.8)　to　45.4%　(95%　CI:　35.9,　54.8).　With　increasing　urbanization　rates,　community　areas　and　younger　adults　contributed　more　to　infection　transmission.　These　findings　could　help　the　development　of　targeted　public　health　policies.　This　article　is　part　of　a　Special　Collection　on　Environmental　Epidemiology.