Abstract: Small unmanned underwater vehicles (UUVs) can be equipped with various sensors, such as hydrophones, to achieve high-precision data acquisition. However, during underwater motion, their dynamic behavior can significantly interfere with sensor signals, thereby degrading measurement accuracy. This paper proposes an experimental method based on a vertical motion apparatus to investigate the vibration-induced interference of small UUV motion on hydrophone measurements. Experiments were conducted in an anechoic water tank using a test model comprising a hydrophone mounted on a dummy body and an accelerometer positioned at the model’s head. Three typical operating conditions were examined: uniform motion, uniformly accelerated motion, and maneuvering (suspended and displacement motions). The experimental results demonstrate that the proposed method and apparatus successfully realize the prescribed motion trajectories and enable quantitative testing of vibration interference from small UUV motion on hydrophone performance under typical operating conditions.