The　price-volume　nexus　is　essential　for　understanding　and　discriminating　the　structure　of　the　carbon　market.　The　current　research　investigates　the　price-volume　dependences　in　the　European　carbon　market　and　Chinese　national　carbon　markets　through　fractal　methods.　The　results　demonstrate　that　prices　have　close　connections　with　volumes　at　multi-time　scales　in　both　markets,　and　that　the　price-volume　correlation　coefficient　series　in　the　Chinese　carbon　market　have　more　intense　volatility,　implying　that　it　is　more　difficult　for　Chinese　investors　to　reach　consensus　on　prices　at　different　time　scales　than　European　investors.　In　addition,　there　are　bidirectional　price-volume　transmissions　in　both　markets.　Interestingly,　in　most　cases,　the　influence　from　volume　to　price　is　much　more　apparent　than　that　from　price　to　volume　in　both　markets,　indicating　that　volume　acts　a　more　important　role　in　the　price-volume　transmission.　Finally,　the　European　price-volume　dependence　has　lower　risk　and　higher　efficiency　than　the　Chinese　price-volume　dependence,　which　is　due　to　the　fact　that　the　European　market　is　more　mature　than　the　Chinese　market.　This　study　has　both　theoretical　and　practical　applications　for　policymakers　and　investors　to　make　optimum　decisions　relating　to　policy　formation　and　risk　management　in　the　carbon　market.