This study reports the discovery of a large alternagnetic splitting of up to 1.0 eV near the Fermi level in CrSb, using synchrotron-based angle-resolved photoemission spectroscopy (ARPES) and model calculations. The alternagnetism in CrSb is characterized by a bulk-type g-wave symmetry, with four spin-degenerate nodal planes crossing the Γ point. The alternagnetic splitting is confirmed through three-dimensional k-space mapping, revealing the alternagnet's symmetry and associated nodal planes. Density functional theory (DFT) calculations accurately reproduce the ARPES results, and tight-binding model analysis shows that the large alternagnetic splitting arises from strong third-nearest-neighbor hopping mediated by Sb ions, which breaks both space-time reversal symmetry and translational spin-rotation symmetry. The large band and spin splitting near the Fermi level in metallic CrSb, combined with its high Néel temperature (up to 705 K) and simple spin configuration, opens up new opportunities for exploring emergent phenomena and spintronic applications based on alternagnets. The study also highlights the importance of interlayer electron hopping mediated by nonmagnetic ions in achieving the large alternagnetic splitting. The results provide insights into the electronic structure and magnetic properties of CrSb, and suggest that alternagnetic materials can be tuned by pressure or strain to enhance their properties. The findings contribute to the understanding of alternagnetism and its potential applications in spintronics and superconductivity.This study reports the discovery of a large alternagnetic splitting of up to 1.0 eV near the Fermi level in CrSb, using synchrotron-based angle-resolved photoemission spectroscopy (ARPES) and model calculations. The alternagnetism in CrSb is characterized by a bulk-type g-wave symmetry, with four spin-degenerate nodal planes crossing the Γ point. The alternagnetic splitting is confirmed through three-dimensional k-space mapping, revealing the alternagnet's symmetry and associated nodal planes. Density functional theory (DFT) calculations accurately reproduce the ARPES results, and tight-binding model analysis shows that the large alternagnetic splitting arises from strong third-nearest-neighbor hopping mediated by Sb ions, which breaks both space-time reversal symmetry and translational spin-rotation symmetry. The large band and spin splitting near the Fermi level in metallic CrSb, combined with its high Néel temperature (up to 705 K) and simple spin configuration, opens up new opportunities for exploring emergent phenomena and spintronic applications based on alternagnets. The study also highlights the importance of interlayer electron hopping mediated by nonmagnetic ions in achieving the large alternagnetic splitting. The results provide insights into the electronic structure and magnetic properties of CrSb, and suggest that alternagnetic materials can be tuned by pressure or strain to enhance their properties. The findings contribute to the understanding of alternagnetism and its potential applications in spintronics and superconductivity.