Abstract: The slowness distribution curves in (100), (010) and (001) for LiB₃O₅ have been plotted. The maximum of acoustic velocities and their directions have also been gained, and they are made comparison with that of LiB₅O₇. Crystal orientation dependence of piezoelectric modulus d₃₃ and electromechanical coupling coefficient k₃₃ have been calculated phenomenologically. The maximum values of piezoelectric modulus d₃₃ and electromechanical coefficient k₃₃ are obtained, and the orientations are also determined. It is found that the values of piezoelectric modulus and electromechanical coefficient for LBO are similar to those of Li₂B₄O₇ and the velocities of acoustic wave are larger than those of Li₂B₄O₇. These results will give certain directions for the application of LiB₃O₅ to the devices of piezoelectricity and acoustic-optics.