Understanding the effect of a catalyst on the growth of nanowires is crucial for their controllable synthesis. In this study, we report the growth of InGaP nanowires induced by different-sized Au catalysts by metal-organic chemical vapor deposition. Through electron microscopy characterization, two types of InGaP nanowires are identified, and the difference in catalyst size is shown to cause their different morphological, structural, and compositional characteristics. Furthermore, the influencing mechanism of catalyst size on the formation of hierarchical structures in nanowires is discussed. This study provides an insight for a better understanding of the growth of ternary nanowires, especially the effect of catalyst size, which can be a promising approach to control the ternary nanowire growth, and is therefore beneficial for the design of the corresponding nanowire-based device.