Effectively　exploring　the　impacts　of　urban　spatial　structures　on　carbon　dioxide　emissions　is　important　for　achieving　low-carbon　goals.　However,　most　previous　studies　have　examined　the　impact　of　urban　spatial　structure　on　total　carbon　emissions　based　only　on　polycentricity.　Fine-grained　studies　on　subsectoral　carbon　emissions　and　other　dimensions　of　urban　spatial　structure　are　lacking.　Therefore,　our　study　comprehensively　explores　the　impact　of　urban　dispersion　and　polycentricity　on　total　carbon　emissions　and　carbon　emissions　of　four　subsectors　(industry,　power,　civilian,　and　transportation)　from　2012　to　2017　while　considering　the　effects　of　city　size.　Results　reveal　that　the　nighttime　light　data　is　useful　for　measuring　urban　spatial　structure,　and　a　polycentric,　decentralized　urban　spatial　structure　correlates　with　the　reduced　total　carbon　emissions　and　transportation　carbon　emissions.　Meanwhile,　a　decentralized　urban　spatial　structure　gives　rise　to　lower　industrial　carbon　emissions　and　civilian　carbon　emissions,　whereas　a　multicenter　urban　spatial　structure　contributes　to　minimizing　carbon　emissions　from　power　systems.　However,　in　small　and　medium-sized　cities,　urban　spatial　structure　differently　affects　the　total　carbon　and　transportation　carbon　emissions.