Abstract: In a buffer medium of pH 4.3,intensity of resonance scattering of the reaction system of chlorophenol red (CPR),human serum albumin (HSA) and sodium dodecyl sulfate (SDS) was significantly decreased by the presence of stannous tin.Linear relationship was kept between the magnitude of decrease in intensity of resonance scattering (ΔI) and concentration of Tin(Ⅱ) in the range of 0.2-4.0 μg·L-1,with the detection limit (3S/N) of 0.12 μg·L-1.In its application to the analysis of 3 water samples,values of RSD′s (n=6) obtained were less than 3.5%.Results of recovery test found by standard addition method were in the range of 95.5%-100.6%.