Based on a study of the influences of the acidity and concentrations of sodium molybdate and malachite green on the colour developing,an improved method for phosphorus analysis by combined malachite green reagent is reported.By testing 10 standard tubes,the results are as the following:s=0.0065 and v=1.26%.This method can be used in the analysis of the activity of Na⁺,K⁺-ATPase etc.