Abstract: A method for the determination of phosphorus in simulated high level liquid waste was established. In the presence of bismuth salt, orthophosphoric acid reacts with ammonium phosphomolybdate to produce phosphomolybdenum yellow（PMo12 heteropoly acid）, which can be reduced to phosphomolybdenum blue by the ascorbic acid. The absorbance was measured on the spectrophotometer to obtain the phosphorus content in the sample. Experiments were carried out on the absorption wavelength of phosphorous molybdenum blue, the formation of acidity, the amount of color reagents, the stabilization time, interference ions, regain recovery, precision, etc. The results show that in 0.8 mol/L nitric acid solution, phosphorous molybdenum is formed completely after adding strontium nitrate, ammonium molybdate, ascorbic acid sequentially, which can stable 40 min in room temperature, λ_max=695 nm. Under the selected experimental conditions, the influence of interfering ions on the determination of 0.2 mg/L phosphorus can be neglected, if the masses of the interfering ions are less than those as shown in the round brackets: Si（0.3 mg/L）, Fe（4.0 mg/L）,Ni（2.9 mg/L）, U（0.8 mg/L）, Ce（0.8 mg/L）, Mg（0.4 mg/L）, Mn（1.0 mg/L）, Al（2.0 mg/L）, Cu（1.6 mg/L）, Nb（0.2 mg/L）, Sr（0.4 mg/L）. The relative standard deviation is less than 3.0%（n=6）, and the recovery of standard addition is 99.80%-103.34%, which meets the requirement of analysis. The method can be used to measure the content of phosphorus in real high level liquid waste.