The commercial piezoelectric accelerometers used in co-vibrating vector hydrophones have the disadvantage of large mass， which limits the performance of vector hydrophones. In this paper， an acceleration sensitive structure based on thickness shear piezoelectric effect is designed， which has the advantages of light weight and high sensitivity. The mass of the acceleration sensitive structure is 0.039 kg. Working frequency band is 20~2 000 Hz. It’s sensitivity is about 3 000 mV/g at 200 Hz. And the maximum lateral sensitivity ratio in working frequency band is less than 8%. A spherical vector hydrophone with the acceleration sensitive structure is tested， which is 72 mm in diameter， the working frequency band is 20~2 000 Hz， and the equivalent sound pressure sensitivity of x， y and z channel are -191.6 dB， -191.4 dB and -191.8 dB at 200 Hz， with direction performance of cosine and good consistency. Test results show that this acceleration sensitive structure is suitable to be used in vector hydrophones. Compared with the vector hydrophone with commercial accelerometer， it is proved that this acceleration sensitive structure can effectively reduce the average density and improve the sensitivity of the vector hydrophone.