Abstract: The determination of classification scheme is one of the important problems about the theory and practice of classification expresion.It includes t o aspects, the determination of classification number,and the selection of classification limits.The number of classification number should be determined based on the scale of population density maps,their mapping purpose,the eharacteristics of population distribution in mapping regions,charting and printing technology and so on.The basic principles of classification limits are that the map surface is scientific,the statistical aecurace is high,and it is convenient for useage.On the basis of the present quantitative standard of statistical map classification, some ne/calculating formulas for classification accuracy:ACAi(N,K)(i=1,2, 3,4,5)ere vorked out,hich are most suitable to population density classification,and give consideration to the statistical accuracy of classification and the mapping effect.And the advantages of the new formulas are proved by the practical example.