Abstract: Abstract: The anatomic structure of the summer leaves and the microstructure in 5 cultivars of citrus were studied. The experimental results showed that the leaf stomata density in lower epidermis was significant different among cultivars and in positive correlation with the disease resistance to Xanthomonas axonopodis pv. citri (r= 0.888). The microstructure of leaf was not significant different among the cultivars and showed no correlation with disease resistance. The stomatal density in leaf tissues could be one of the criteria for canker resistance of citrus.