Nonlinear optical (NLO) materials are designed based on fundamental building blocks (FBBs) with excellent microscopic properties, which is conducive to obtaining high-performance materials. Here, the [B₃O₇] group similar to the [B₃O₆F] group is considered to have excellent microscopic properties. According to this, a structure with FBBs of [B₃O₆F]: Li₂B₃O₅F is designed. Li₂B₃O₅F is capable of achieving deep-ultraviolet (deep-UV) transparency with short absorption edges below 200 nm (E_g = 6.37 eV). The birefringence is 0.10@1064 nm, which brings a short phase-matching (PM) wavelength of about 195 nm. Finally, the relationship between structure and performance of Li₂B₃O₅F is clarified by first-principles calculation.