PMA-Malachite　Green　Spectrophotometry　plays　a　role　in　measuring　micro-amount　phosphorus,　but　in　the　concentration　of　phosphorus　range　from　1　to　10　μg/L,　the　effect　is　not　fairly　good.　This　paper　presents　a　revised　measurement　through　some　aspects　such　as　adjusting　the　concentration　of　samples＇　type　curve,　optimizing　the　developer　compounds,　reviewing　the　effect　of　different　solution　course　of　malachite　green　and　different　doses　of　surfactant　to　the　measurement　and　re-measuring　the　wavelength　of　maximal　absorbance　of　associated　system.　The　results　indicate　that　the　revised　measurement　of　PMA-Malachite　Green　Spectrophotometry　is　good　at　measuring　trace　amount　phosphorus　concentration　range　from　0　to　50　μg/L,　which　has　qualities　of　high　degree　of　sensitivity　and　precision　and　of　long　stably　time.　Especially,　the　advantage　of　revised　measurement　is　evident　in　concentration　range　from　1　to　10　μg/L,　which　is　equal　to　measure　the　trace　amount　phosphorus　in　potable　water.