Abstract: According to the Meso-piezoresistance effect and acoustics theory of cylinder,a novel vector hydrophone based on thin film of quantum well is introduced in this paper.It is desirable that the application of thin film of quantum well and ingenious structure of the hydrophone may improve the low-frequency sensitivity of the vector hydrophone as well as its miniaturization.The Meso-piezoresistance effect and acoustics theory of cylinder are briefly described.The design and encapsulation of the hydrophone are completed.The test results are presented at last.The experiment results show that the proposed vector hydrophone can detect the vibrating velocity information of particles in sound field,and possesses directional pattern in form of "8"-shape.Also it has other several advantages such as small volume,light weight as well as low cost and so on.