在对昆明某地玄武岩红土进行现场勘察的基础上 ,对其剖面的物质组成取样进行了研究 .结果表明 :玄武岩红土剖面的物质组成由地表向下呈有规律的变化 ,化学成分以SiO2 ,Fe2 O3,Al2 O3为主 ,随剖面深度的增大 ,SiO2 逐渐增大 ,Fe2 O3和Al2 O3逐渐减少 ;烧失量、pH值、比表面积、阳离子交换量都逐渐减小 .颗粒组成上细下粗 ,具中等分散性 ,粘粒含量不高 ,天然含水率小 ,土颗粒密度大 ,低塑性 ,不具膨胀性 ,有一定崩解能力 .这充分反映了同一剖面上红土化作用从上到下逐渐减弱的变化规律 Based on the field investigation of the basalt red clay in a certain area of ​​Kunming, the material composition sampling of the profile was studied.The results show that the composition of the basalt red clay profile changes regularly from the surface to the bottom, and the chemical composition is SiO2, Fe2 O3 and Al2 O3, and gradually increase with the increase of the depth of the section, Fe2 O3 and Al2 O3 gradually decrease, and loss on ignition, pH value, specific surface area and cation exchange capacity decrease gradually. Coarse, moderately dispersible, clay content is not high, the natural moisture content is small, the soil particle density, low plasticity, non-swelling, have some disintegration ability.This fully reflects the same section on the role of the laterite from top to bottom Gradual decline of the law of change