The deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystal NaBe2BO3F2 (NBBF) is grown by the spontaneous nucleation method with the dimensions up to 20 x 20 x 1.5 mm(3). The crystal structure was determined using single-crystal x-ray diffraction analysis and its space group was defined as C2, which belongs to the biaxial class. The optical properties including the transmittance and the NLO coefficients were first determined. The band structure and density of states of NBBF were also calculated. Based on the calculated refractive indices, the Sellmeier equations were fitted to evaluate its ability for deep-UV laser generation. Our results suggest that NBBF is a viable deep-UV NLO crystal.