A new ultraviolet nonlinear optical crystal, LiSr₃Be₃B₃O₉F₄ (LSBBF), was obtained by the flux method. LSBBF is isostructural to NaSr₃Be₃B₃O₉F₄ and inherits its brilliant [Be₃B₃O₁₂F]¹⁰⁻ structural units. It exhibits a considerable second-harmonic generation (SHG) intensity (∼2.2 × KDP) and short ultraviolet cut-off wavelength (∼175 nm). Further theoretical calculations revealed that the shortest SHG phase-matching wavelength of LSBBF is down to ∼245 nm. These results indicated that LSBBF has potential to be used for the 266 nm output of the fourth harmonic of Nd:YAG lasers.