Leaf architecture of 18 species and 3 varieties of Euodia s.l. (Rutaceae) in China was observed under a stereomicroscope. The primary vein framework is pinnate venation pattern. In most species, the secondary veins are festooned brochidodromous and simple brochidodromous. Very few species are present interior secondaries. Intersecondary veins are absent or present. Tertiary veins are irregularly reticulate or very few weakly percurrent, with marginal tertiary veins being annular. Quaternary veins are irregular reticulate. Quinternary veins are irregular reticulate or freely ramifying. Areolation is poor or moderate developed. Freely ending veinlets of most species are simple or tracheoid idioblasts. Marginal ultimate veins in most species are incomplete, and a few are annular. A key to the sections of Euodia s.l. is presented mainly based on some important external morphological features and leaf architecture characteristics. The results show that the structures formed by the secondary veins and higher veins of these Euodia groups are very stable at the genus level, and there are some interspecific differences. Therefore, the leaf architecture characteristics of Evodia could provide evidences for more accurate identification of some difficult and confused species, which have important taxonomic significance.