A method for determination of trace lead in blood with complex catlysis polarography was develop. The peak potential of lead is -0.54 V in the system of hydrochloric acidpotassium iodide-vanadium (IV)-ethanol-ascorbic acid. There is good linelar relationship between peak current and lead concentration in the range of 0-1.0 microgram/3 ml. The recoveries of spiked samples ranged from 76.0% to 105.0% and the average recovery was 91.0% with RSD of 3.6% to 7.0%. The detection limit was 45 micrograms/L. The blood samples of 24 normal people and 6 workers with occupational exposure to lead were measured and the results were concordant with the clinical diagnoses. The proposed method is simple, rapid, sensitive and reliable. It is suitable for determination of trace lead in blood.