In　this　paper,　the　analysis　on　the　complexity　characteristic　of　traffic　flow　system　is　deepened　through　introducing　characteristic　quantities　of　complexity,　such　as　Lempel-Ziv　complexity,　statistical　complexity,　approximate　entropy,　and　combining　the　criterion　methods　of　chaos　&　fractal.　The　Lyapunov　index,　relevancy　dimension　and　their　complexity　characteristic　quantities　of　actual　traffic　flows　are　calculated.　By　virtue　of　the　calculation　results,　some　useful　conclusions　are　obtained.　Copyright　ASCE　2007.