When potassium picrate (KP) and KClO₄ are dissolved in water, the solution obtained is bright yellow for the former and colorless for the latter in appearance. With the help of this characteristic, the content of KP in KP-KClO₄ ignition composition is determined by spectrophotometry analysis. The determining conditions is discussed, and the relationship between the absorbance and the concentration of KP is also studied. Results show that the uncertainty and the inaccuracy of the experimental data are 0.2% and 1.3%，respectively, which indicate that the method of determining the content of KP in KP-KClO₄ ignition composition is convenient and feasible for the system.