【Objective】The present experiment was conducted to screen the best matrix modifier for determining the Pb content in plant food samples using electrothermal flameless graphite furnace atomizer and to improve the accuracy of graphite furnace atomic absorption spectrum. 【Method】Palladium （Pd） and platinum （Pt） salts were used as matrix modifier to determine the Pb content using standard method to analyze their effects and the best ashing and atomization temperature and dosage. 【Result】The results showed that the Pd matrix modifier had significant effect on increasing 200-300℃ of atomization temperature and lower atomization loss of Pb under low temperature （＜900℃）， and the recovery rate was 80-113%， while the Pt matrix modifier did not show significant improvements. 【Conclusion】Palladium can be used as matrix modifier to determine the Pb content in samples with complicated component and the best ashing temperature is 500℃， the optimum atomization temperature is 2200℃， with the working volume 25 mg/L.