In order to solve the problem that the existing single-mode-drive USMs either move unidirectionally or wear and tear seriously, a single-mode-drive and tower-shaped USM that can move bi-directionally is presented. The USM is composed of an asymmetric stator and a mover, and the stator is designed as an asymmetric Langevin vibrator. A low-order and a higher-order asymmetric working mode is utilized to the stator, and the scheme of PZTs′ polarization and arrangement location are designed accordingly. Switching between the low-order and the higher-order mode can drive the motor bi-directionally by the single mode. Firstly, the working principle of the motor is analyzed. Then the prototype of the motor is fabricated. Finally, the tests of vibration mode and mechanical characteristics on the prototype are accomplished. Experimental results show that under the condition of single phase excitation through phase A, the motor is working under the low-order mode, and the mover is driven forward with the maximal velocity of 112mm/s and the maximal driving force of 2N; under the condition of single phase excitation through phase B, the motor is working under the higher-order mode, and the mover is driven backward with the maximal velocity of 94 mm/s and the maximal driving force of 3N.