YCa4O (BO3) 3 (YCOB) crystal has superior nonlinear optical properties, high temperature piezoelectric properties and good chemical stability, compared with LBO crystal, the crystal has the following advantages: Crystal is not easy to moisture solution; Effective nonlinear optical coefficient is 37.5% larger than the former; temperature allowable range is 22 times wider , Although laser damage threshold is similar, but the parametric fluorescence is less than three orders of magnitude, the coefficient of thermal expansion is small and the anisotropy is small, and the processing performance is better. he crystal can be grown by the Czochralski method grow, has a short growth cycle and is relatively low in cost, and is advantageous for obtaining a crystal capable of producing a large-caliber laser device. The large-diameter laser device made of this crystal enables frequency multiplication (SHG), triple frequency (THG), optical parametric oscillation (OPO), optical parametric amplification (OPA), and optical parametric chirped pulse amplification (OPCPA) in high energy and high power laser systems.