Introduction of the coplanar BO3 triangles in the alkali metal and alkaline-earth metal mixed fluoborate generates a new UV nonlinear optical material [Li3Ca9(BO3)7]·2[LiF] (LCBF), which possesses a moderate SHG response as large as that of the KDP and a wide transparent region with a UV cutoff edge at 230 nm. The first-principle theoretical calculation suggests that LCBF has a relatively large birefringence (0.07; 532 nm). These properties make it a potential UV nonlinear optical material. And interestingly, LCBF is a salt-inclusion borate with the Li-F chains residing in the one-dimensional open framework, which caters to the development of the salt-inclusion compound in borate.