In　the　background　of　the　rapid　urban　development,　the　conflict　between　population,　economy,　and　environment　are　intensified　and　appear　complexity.　Based　on　the　features　of　city,　the　index　system　was　set　up　to　reflect　the　development　of　city.　The　coordinate　assessment　system　of　population,　economy,　and　environment　is　established　in　the　scale　of　city　size　by　principal　component　analysis,　etc.　The　demonstration　analysis　took　Beijing　as　example.　Finally,　on　the　basis　of　the　status　of　comprehensive　evaluation　indexes　and　coordination　degree　of　the　district,　the　main　problems　in　the　sustainable　development　of　Beijing　were　found　out　and　some　suggestions　were　also　proposed.　©　2010　IEEE.