Abstract: In order to study the optical parametric characteristics of KBe2BO3F2,according to dispersion equation of nonlinear crystal,momentum and energy conservation,the angle tuning curves and range of wavelength in type-Ⅰ and type-Ⅱ were obtained through numerical simulation,which were compared with those of CsLiB6O10.It can be seen that KBe2BO3F2 is an excellent nonlinear crystal to obtain ultraviolet continuous tunable output and the shortest wavelength 220nm can be obtained when the pump wavelength is 213nm in type-Ⅰ.