The basic principles of the gradient fiber optic vector hydrophone are elaborated, and the effects of component sensitivity and distance impact on the acoustic pressure sensitivity are analyzed. The structure design of the 3D gradient fiber vector hydrophone is completed. Samples of two-dimensional gradient fiber optic vector hydrophones were manufactured and technically tested. Test results indicate, in the frequency range of 20~1000Hz, the acoustic pressure sensitivity of the gradient fiber vector hydrophone is basically consistent with the theoretical value, and its presents good directivity at 500Hz.