NLO materials design due to the conflicting and harsh performance requirements. [5] Borates with unique structures are a rich source for optical materials. [6] In our previous work, a fluorine-directed material design strategy was proposed to explore birefringent and NLO materials with outstanding properties in the borate system. [7] It has been elucidated that the introduction of fluorine into borates can effectively enrich the structural chemistry and regulate the optical properties. First, from the structural point of view, the incorporation of fluorine into borates constructs borate fluorides and fluorooxoborates which greatly broaden the structural types and increase the probability of achieving non-centrosymmetric structures. [8] Second, the oxyfluoride groups [BO x F 4−x ] (x = 1, 2, and 3; represented by [BOF] below) exhibit stronger polarizability anisotropy and hyper-polarizability than [BO 4 ], which are conducive to improving birefringence and NLO efficiency. [9] Moreover, [BOF] groups possess large HUMO-LUMO gaps, which are beneficial to generate large band gaps and obtain UV transparent materials. [9,10] Guided by the fluorine-directed strategy, a series of UV/deep-UV fluorooxoborate birefringent crystals including M