Excimer　laser　ablation　technique　was　introduced　into　this　work　to　fabricate　a　passive　planar　micromixer　on　the　PMMA　substrate.　T-junction　shaped　and　width-changed　S-shaped　microchannels　were　both　designed　in　this　micromixer　to　enhance　mixing　effect.　The　mixing　experiment　of　distilled　water　and　Rhodamine　B　with　injection　flow　rate　of　500　and　1,500　mu　m/s　validates　the　mixing　effectivity　of　this　micromixer,　and　indicates　the　feasibility　of　excimer　laser　ablation　in　the　microfabrication　of　mu-TAS　device.