Direct ethanol fuel cell (DEFC) has been widely studied because of its advantages of easy fuel availability, green and high effiency. However, DEFC catalysts are still frustrated with low catalytic efficiency and poor catalyst stability, which restrict its rapid development. In this work, XC-72R carbon black-loaded Pt₁Co_x/C high-index crystalline nanocatalysts were prepared in one step by liquid-phase hydrothermal synthesis, using polyvinylpyrrolidone (PVP k-25) as dispersant and reducing agent, glycine as surface control agent and co-reducing agent, and modulating the molar ratio of Pt-Co metal precursors to achieve the in-situ growth of catalyst particles on carbon carriers. The exposed high index crystalline facets of the Pt₁Co_1/3/C nanocatalyst mainly consisted of (410), (510) and (610) crystalline facets. The growth pattern of the Pt₁Co_1/3/C nanocatalyst grains varied from 'sphere-like' to cubic, and eventually to concave with high index grain orientation. The Pt₁Co_1/3/C nanocatalyst with high index crystalline surface has the highest electrocatalytic activity with an electrochemically active surface area of 18.46 m²/g, a current density of 48.70 mA/cm² for the ethanol oxidation peak, a steady state current density of 8.29 mA/cm² and a potential of 0.610 V for the CO oxidation peak. This indicates that the defect atoms such as steps and kinks on the surface of the catalyst with high index crystal plane can increase the active sites, thus showing excellent electrocatalytic performance. This study may provide a theoretical basis for the development and industrial application of high index crystalline catalyst materials.