This paper presents the comparison of the preparation methods of plant tissue for electron microprobe x-ray analyzer.It has been shown that epidermis and cortex of maiu root were apparently shriveled with air drying method.Large amount of K and Ca were removed out of the root prefixed for 1 hour with 4% glucaraldehyde.Only with freezinglrying technique at about 5×10^-4 Torr and below -800C,could the morphology of the sample obtained be kept in original feature and elements be kept in situ;besides,this method was high in efficiency.Results obtained from the samples prepared with this method and investigated by electron microprobe showed that a considerable amount of K was detected within the cells of cortex and endodermis and an eVen larger amount of K was concentrated in the stele.But Ca was accuntulated in the cortex and the endodermis and little was found in the conducting tissue of root.A rather high concentration of Si was also observed in,the tissues outside the endodermis of the root.This indicates that soil particles enter the root and thus the endorhizosphere is formed after the cells of the epidermis and the cortex have been destroyed by the soil microbes.