The development and evolution of karst environment have been recorded in latecritic layer, therefore, latecritic layer is the important subject of research for soil and environmental evolution in karst area. On the base of study on latecritic features, rare earth elements and trace elements of 3 latecritic profiles in Guiyang City, writer suggests that latecritic layer be divided into two subunits, e.g. the lower unit: brown latecritic unit, supperriched in REEs, Be, Sr, Nd, Sm, and the upper unit: yellow latecritic unit, poor in REEs, and trace elements. It is shown that rare earth elements and trace elements migrated from the upper unit to the lower unit. Therefore, dating age of latecritic layer is difficult by Be, Sr, Nd, Sm and Pb isotopic method. Additionally, the supperrich in heavy metal and radioactive elements, U, Th, Rn, in the brown unit (Lower unit) was discovered, which suggests that the environmental protection must be keep up with municipal engineering.