A new nonlinear optical crystal of sodium terbium borate (Na2.67Tb2.11B3O9, Mr = 573.14) was synthesized by solid reaction method. The colorless transparent single crystals were grown from the high temperature solution by employing NaBO2 as flux. The structure was deter- mined by single-crystal X-ray diffraction method. The compound crystallizes in the orthorhombic system, space group Amm2 with a = 5.0744(10), b = 10.990(2), c = 6.9078(14) A, V = 385.24(13) A3, Dc = 4.941 g/cm3, F(000) = 250, Z = 2, μ= 9.205 mm-1, the final R = 0.0253 and wR = 0.0610. Its three-dimensional network structure is constructed from isolated BO33-, Na(1)O8, Na(2)O6, Na(3)O6 and Tb(1)O9 polyhedra. Variable-temperature magnetic susceptibility measurements show the compound is paramagnetic (μj = 7.04 μb). The intensity of the second harmonic generation of Na2.67Tb2.11B3O9 is 2.5 times that of KDP.