Abstract: The present experiment was carried out in south Fujian during 1985-86,in order to find out the optimum range of the major nutrient contents in the leaves of Fuyan longan,which variety covered the largest cultivated area in Fujian.It was found that the amount of the mineral elements in the leaves of the same cultivar was affected by different localities and years for sampling.Thus,representative foliar samples should be collected at more orchards and in more years so as to define diagnostic criteria. The results from the statistical analysis indicated that the difference in the variation coefficients of the element contents in the leaves was pronounced, so that this characteristic of different variation coefficients and possible factors that affect the nutrient diagnosis of the leaves should be comprehensively considered to achieve better results.The preliminary study suggested that the values of the optimum range of the mineral elements in the leaves of summer shoots of Fuyan longan were : N 1.5-2.0%, P 0.10-0.17%, K 0.40-0.80%, Ca 0.70-1.70%, Mg 0.14-0.30 %; and that the optimum ratio between the amounts of elements in the leaves was N : P : K : Ca : Mg= 1 : 0.08 : 0.34 : 0.69 : 0:13.The above diagnostic criteria may provide the parameters of fertilizer guide for Fuyan longan.