Abstract: Genetic diversity and differentiation of three Quercus variabilis natural populations in Shaanxi Province were studied at the enzyme level.Using gel electrophoresis method we determined the isoenzyme patterns of peroxidase(POD),esterase isozyme(EST),malate dehydrogenase(MDH) and alcohol dehydrogenase(ADH),and analyzed the proportion of polymorphic loci,average of allele,the allelic frequency,expected heterozygosity and coefficient of gene differentiation.It was showed that 95.1% of total gene diversity resided within the natural populations,and only 4.9% of the total genetic variance was among the populations.75% loci were detected to be polymorphic depending on the criterion of polymorphism.The average number of alleles detected per locus was 2.708.The mean value for all samples of the average expected heterozygosity was 0.388.