The　＇Urban　sprawl＇　is　a　big　problem　that　from　1960s　western　countries　have　had　to　deal　with.　But　what　is　＇Urban　sprawl＇　and　how　to　measure　it　different　scholars　of　different　schools　have　different　points　of　view.　Based　on　analyzing　the　definition　of　urban　sprawl　by　western　scholars　systematically,　the　author　gives　a　general　definition　of　urban　sprawl.　The　author　points　out　their　limitation　and　applicability.