The contents of Cd,Hg,As,Cu,Zn,Pb,Co,Mn,Ni,Cr,Li,Fe,Ti,Ca,Sr and Zr in 91 samples of soils developed on alluvial deposits in Tianjin region were determined by Xray fluorescence and colorimetry and their mechanical compositions were determined by gravimetry.The correlation between the rnntents of those elements and machanical compositions of the soils were studied,and the data obtained indicate that the soil particles with 0.01 mm diameter is a obvious critical limit.