Abstract: The present paper deals with the process of preparing the standard material of forest soil. 3 samples should be used in the research: calcareous cinnamon alkaline soil, yellow-red acid earth and a botanicalsample——leaf of Chinese fir (Cunninghamia lanceolata). 2 mm size soilsamples were stirred evenly by Y-shaped method, 0.149 mm size soil samples and 0.177 mm botanical samples were prepared by a high alumina porcelain ball mill. High temperature was used to kill the microorganisms in the soil sample; 60Co radiation was used to kill the microoganisms in the botanical sample. The groups and quantities of microorganisms in the standard samples were analysed, when the testing of stability of the samples was conducted for two years. Homogeneity and stability of standard samples was tested by F test and analysis of variance. The result of the homogeneity and stability of test has met the demand of standard samples. The method of 2 mm size soil particles used for available nutrients determination was reported for the first time in China.