The　accurate　estimation　of　traffic　states　of　the　road　traffic　network　can　provide　decision-making　for　both　travellers　and　traffic　managers.　In　this　paper,　an　algorithm　based　on　compressive　sensing　is　presented　to　estimate　traffic　states　of　the　road　traffic　network.　Firstly,　the　compressive　sensing　theory　is　presented.　Then　to　make　sure　that　the　compressive　sensing　theory　can　be　applied　to　the　estimation　of　traffic　states　of　the　road　traffic　network,　the　compressibility　analysis　of　the　road　traffic　states　data　is　discussed.　Finally,　the　road　traffic　states　estimation　approach　based　on　compressive　sensing　is　presented.　The　applications　of　this　road　traffic　states　estimation　algorithm　are　also　discussed.　One　typical　road　network　in　Beijing　is　adopted　for　case　studies.　The　final　results　of　the　experiments　are　listed,　which　prove　that　this　traffic　states　estimation　approach　based　on　compressive　sensing　is　feasible　and　can　achieve　a　high　accuracy.