Single crystals of Ba3B6O11F2 have been synthesized by introducing the F- anion into the BaO-B2O3 system and the structure was determined by single-crystal X-ray diffraction. It crystallizes in the noncentrosymmetric space group P2(1) (no. 4). In the structure, a new fundamental building block, the B6O14 group, was observed. The second harmonic generation (SHG) measurement shows that Ba3B6O11F2 possesses a large SHG response about three times that of KH2PO4 (KDP) and is phase-matchable. In addition, it exhibits a wide transparency range with a short UV cut-off edge (<190 nm), which suggests that the material is a potential deep UV nonlinear optical material.