In this work, to improve the sensitivity of lateral field excited (LFE) sensors to changes of liquid conductivity, LFE bulk acoustic wave sensors with interdigital electrodes are investigated. LFE bulk acoustic wave on thickness-shear mode is excited successfully by interdigital electrodes on (yxl)88° LiTaO3 and applied in liquid-phase sensor. The electric field direction of LFE (yxl)88° LiTaO3 plates is determined. Based on this, several LFE bulk acoustic wave sensors with interdigital electrodes are designed and fabricated to increase the sensitivity of LiTaO3 LFE sensors. The results show that the (yxl)88° LiTaO3 LFE sensor with interdigital electrodes is 10.9 times and 2.1 times more sensitive to changes in liquid conductivity compared to traditional LFE devices with single gap circular electrodes and Archimedes spiral electrodes, respectively. The results are important for investigating high-sensitivity LFE bulk acoustic wave sensors by using LiTaO3 crystal.