In　view　of　the　inadequateness　that　exists　in　standards　and　specifications　for　freeway　service　area　in　China,　this　paper　carried　out　research　on　the　layout　problems　related　to　freeway　service　areas.　Firstly,　the　freeway　service　areas　were　categorized　into　3　types　according　to　the　area＇s　function　and　size,　and　then　their　corresponding　function　characteristics　and　scales　were　described　qualitatively　and　quantitatively.　Secondly,　the　factors　influencing　freeway　service　areas　were　determined　as　freeway　type,　traffic　volume　and　drive-in　rate,　vehicle　property,　the　landscape　along　freeways,　function　coordination.　Thirdly,　this　paper　set　a　distance-based　optimizing　model　for　single　freeway　service　area　layout,　and　then　put　forward　the　optimization　criteria　and　procedure　for　service　areas　of　freeway　network.　Finally,　the　theory　was　validated　by　applying　the　layout　optimization　model　with　Hubei　Province.　©　2011　ASCE.