A potassium fluoborate compound, a potassium fluoborate non-linear optical crystal, a preparing method of the crystal and uses of the crystal are provided. The chemical formula of the compound is KB4O6F, the molecular weight of the compound is 197.34, and the compound is prepared by a solid-phase synthetic method or a vacuum encapsulation method. The chemical formula of the crystal is KB4O6F, and the molecular weight of the crystal is 197.34. The crystal belongs to an orthorhombic system, and the space group of the crystal is Pna2<1>. According to cell parameters, a=7.4638 angstroms, b=11.2913 angstroms, c=6.5089 angstroms, alpha=beta=gamma=90 degrees, and the unit-cell volume is 548.54 angstrom<3>. The frequency-doubled effect of the crystal is 1.8 times of that of KH2PO4 (KDP), and the ultraviolet absorption edge is shorter than 190 nm. The crystal grows by adopting a melt method, a high-temperature melt method, a vacuum encapsulation method, a hydrothermal method or a room-temperature solution method. The crystal has good chemical stability, and can be applied as an ultraviolet and deep ultraviolet non-linear optical crystal in all-solid-state lasers.