In the search for alternatives to conventional Pt electrocatalysts, we synthesized a series of graphene nanoplate (GNP)-supported Pt3Cu1 nanocrystals (NCs), possessing almost the same composition but different morphologies to probe their electrochemical properties as a function of morphology for the ethanol oxidation reaction. The morphology of the Pt3Cu1 catalysts could be systematically evolved from dendritic (D-Pt3Cu1/GNPs) to wire-like (W-Pt3Cu1/GNPs) and spherical (Pt3Cu1/GNPs) by only varying pH of the reaction solution. The as-prepared Pt3Cu1 catalysts were subsequently characterized using a suite of techniques including transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray photoelectron spectroscopy (XPS) to verify not only their morphologies and chemical compositions but also the incorporation of Cu into the Pt lattice, as well as physical structure and integrity. Gratifyingly, the three Pt3Cu1 catalysts exhibited superior electrocatalytic properties for the ethanol oxidation compared to the monometallic Pt/GNPs and Pt/C-JM (Johnson Matthey), with the activities, durabilities and anti-poisonous abilities following the order Pt3Cu1/GNPs < W-Pt3Cu1/GNPs < D-Pt3Cu1/GNPs.