Since the beginning of the 21st century, the third generation wide band gap (E_g>2.3 eV) semiconductor materials represented by gallium nitride (GaN) and zinc oxide (ZnO) are becoming the core supporting materials for development of semiconductor industry. Due to difficult growth and high cost of GaN and ZnO single crystal, epitaxial technology is always used as the substrate materials to grow GaN and ZnO films. Therefore, it is crucial to find an ideal substrate material for the development of third generation semiconductor. Compared with traditional substrate materials, such as sapphire, 6H-SiC and GaAs, scandium magnesium aluminate (ScAlMgO₄) crystal, as a new self-peeling substrate material, has attracted much attention because of its small lattice mismatch rate (~1.4% and ~0.09%, respectively) and suitable thermal expansion coefficient with GaN and ZnO. In this paper, based on structure of ScAlMgO₄ crystal, the unique trigonal bipyramid coordination and natural superlattice structure, the basis for its thermal and electrical properties, are introduced in detail. In addition, the layered structure of ScAlMgO₄ crystal along the c-axis makes it self-peeling, which greatly reduces its preparation cost and has a good application prospect in the preparation of self-supported GaN films. However, the raw material of ScAlMgO₄ is difficult to synthesize, and the crystal growth method is single, mainly through the Czochralski method (Cz), and growing techniques now in China lag far behind that in Japan. Therefore, it is urgent to develop a new growth method of growing high quality and large size ScAlMgO₄ crystals to break the technical barriers.