A new UV nonlinear optical crystal NaSr3Be3B3O9F4 with dimension up to 13×14×20 mm3 was successfully grown by the top-seeded solution growth method from LiF-NaF-B2O3 flux for the first time. The crystalline morphological faces are mainly (101), while (021) or (1 @#x0305;32) faces may occur depending on the direction of the seed applied. Its crystalline quality of the as-grown crystal was evaluated by the x-ray rocking curve with the full-width at half-maximum being 0.013°. By a minimum deviation method, the refractive indices are measured from 235 to 2325nm and fitted to the Sellmeier equations. Furthermore, the hardness, density and chemical stability of the crystal were also reported.