The optimum conditions for the determination of trace Pb and Cd in water treatment reagent by graphite furnace atomic absorption spectrometry were studied in detail in this paper. The results show that the long and tedious pretreatment process was cut down by calibrating background with D2 lamp and NH4H2PO4 as matrix modifier. The determination limits were 0.65 μg·L-1 and 0.12 μg ·L-1 for (Pb and Cd) and linear ranges were 0-50 μg·L-1,0-20 μg·L-1 for Pb and Cd, respectively. Rate of recovery was 90%-110%. This method is accurate, quick and simple, and can be used successfully to determine actual samples.