Urban　evaporation,　as　an　essential　part　of　local　water　vapor　resources　in　urban　areas,　has　often　been　underestimated.　One　possible　reason　is　that　the　evaporation　of　urban　hardened　surfaces　is　seldom　considered　and　poorly　understood　in　urban　evaporation　estimation.　This　study　focused　on　the　mechanisms　and　calculation　of　evaporation　on　hardened　surfaces　in　urban　areas.　Experimental　monitoring　was　used　to　monitor　the　processes　and　characteristics　of　evaporation　on　hardened　surfaces.　Mathematical　models　based　on　water　quantity　constraints　were　built　to　calculate　evaporation　of　hardened　surfaces.　The　results　showed　that:　The　interception　abilities　for　rainwater　and　rainfall　days　of　impervious　hardened　surfaces　determine　their　evaporated　water　amount,　which　means　no　water,　no　evaporation　for　the　impervious　surfaces.　The　greater　evaporation　of　artificial　sprinkling　on　roads　happened　in　fewer　days　of　rainfall　and　frost.　The　evaporation　of　pervious　hardened　ground　is　continuous　compared　to　the　impervious　surface.　Its　soil　moisture　in　the　sub-layer　of　permeable　concrete　decreases　periodically　with　a　period　of　one　day.　The　evaporation　of　hardened　surfaces　occupies　16-29%　of　the　total　amount　of　evaporation　in　the　built-up　areas　in　cities.　Therefore,　the　hardened　surface　evaporation　has　great　significance　on　the　urban　hydrological　cycle　and　urban　water　balance.