Generally, heavy metal hays a tendency to 1.e enriched in the clay of soil, but from the preliminary study on the relationships between some heavy metals and the mechanical composition of soil, together with the composition of minerals in the soils of Hainan Fsland, it was found that the clay fraction of latosol was not enrich by heavy metals, whereas with decreasing particle size of paddy soil that was situated on the same tropical landscape as the latosol was, concentrations of the heavy metals increased and it was highest in the clay fraction(<0.001mm). In order to reveal the cause of the distribution of heavy metals, the different fractions of particle-sizes of the soils were identified by x-ray diffration. The silt group and sand group of the latosol contained large amount of iron oxides, Lut its clay group mainly consisted of kaolinite and gibbsite. Therefore, the distribution characteristic of heavy metals in the latosol is closely relative to iron oxides adsorbing a.u containing heavy metal. However, X-ray diffration analyses showed that with the incerase of particle size of paddy sail, its heavy metal content decreased, which is reaafed to quartz and feldspar increasing and clay minerals decreasing with the increasing of particle size of the soil. The distribution of heavy metals in the paddy soil conforms to that of other soils.