Abstract: Auxin efflux carrier proteins（PIN-FORMED, PINs）are secondary transporters that facilitate efflux of plant signaling molecule auxin from cells．They play pivotal roles in multiple developmental processes in plants, including embryogenesis, organ formation, and tissue differentiation．Research progress in understanding structure, evolution, and functions of PIN proteins was reviewed．It aims to provide insights for further research on plant PIN proteins functional analysis and to identify novel targets for crop improvement through gene editing and other biological breeding approaches．