Lead content in radix astragali was directiy determined by using solid suspension sampling and graphite furnace atomic absorption spectrometry(GFAAS). During the experiment, through the research on the suspension, lead standard solution and ashing rules of radix astragali, the method of matrix modifier was chose with no loss of lead, increasing ashing temperature and reducing the background absorption as the premise. The optimum experimental conditions are 0.5% Mg-(NO3)2 and 0.2% NH4H2PO4 can be used as the matrix modifier of radix astragali suspension, ashing temperature is 750 ℃. Under the optimum conditions, the content of lead in radix astragali is 5.33 mg/kg, the detection limit is 0.26 ng/mL, and the recovery is from 96%～ 99%.The method provides a basis for the selection of matrix modifier using the solid suspension sampling－ GFAAS.
