Abstract: Plants modulate their shoot architecture by regulating activities of the shoot apical meristem and axillary meristems. Meristem activities are regulated by a network of environmental information, developmental stage and genetic makeup of the plant. The fate of signal integration, to a large extent, depends on the action of plant hormones. Auxin plays an essential role in the establishment and maintenance of the apical dominance, which is a central issue in regulating shoot branching. This review focuses on recent advances in the study of auxin biosynthesis, metabolism, polar transport, and signaling pathway, as well as their involvements in the control of the architecture of aerial parts. Prospects in the field are also briefly discussed.