Abstract: Determination of mercury in Sn solders and button batteries by micro-hydride generation cold atomic absorption spectrophotometry was reported in this paper. In acid medium Hg2+ was reduced to Hg by KBH4. The mercury vapor was carried into quartz absorption tube by carrier gas and determined by atomic absorption spectrophotometry at 253.7 nm. The experimental conditions and interference from coexisting ions were studied. The detection limit of the method for Hg is 0.34 ng/mL and the recoveries of standard addition are in the range of 94.4%～104.7% with precision of <6%RSD(n=11). The method has been applied to the sample analysis with satisfactory results.