In order to promote the application of BaTeMo2O9crystal in piezoelectric transducer, the cut directions of single modes of BaTeMo2O9were studied by numerical calculation. On the basis of the experimental data, single modes of thickness vibration were calculated by solving piezoelectric stiffened Christoffel equation in rotating coordinate systems. The cut directions of single modes were determined. The results indicated that a pure longitudinal mode and a pure shear mode could be obtained by y-cut and x-cut with the corresponding electromechanical coupling constant 0.625 0 and 0.292 1, respectively, Pure shear modes could also be acquired by(zyl-θ cut where the value of θ was arbitrary. The electromechanical coupling constant was up to 0.986 9 when θ was 27.77 degree. In addition, wave velocity corresponding to the cut directions were also presented in detail.