By　choosing　relativity　roughness　as　the　small　parameter,　perturbation　equations　of　laminar　flow　in　micro-channel　between　two　parallel　plates　were　set　up.　The　perturbation　equations　were　analyzed　by　the　method　of　Fourier　analysis　and　solved　numerically.　The　computing　results　show　that　the　main　factors　affecting　the　flow　pattern　are　relative　roughness　and　spatial　wave　number　of　wall　rough　curve.　If　the　wave　number　keeps　constant　and　the　relative　roughness　increases,　the　peak　of　the　disturbed　non-dimensional　stream　function　increases　and　the　disturbed　area　in　flow　field　is　invariable.　If　the　relative　roughness　keeps　constant　and　the　spatial　wave　number　decreases,　both　the　peak　of　disturbed　stream　function　and　disturbed　area　in　flow　field　increase　simultaneously.　Because　of　the　existence　of　rough　elements,　obvious　vortex　structures　occur　in　the　flow　field　near　the　wall.　The　vortex　structures　make　viscous　dissipation　augment　and　lead　to　the　friction　loss　flowing　in　micro-channels　larger　than　that　in　macro-channels　under　the　same　conditions.