Abstract: Conventional techniques for detecting in oil wells have been disadvantageous due to their complex process, long production period, high cost and low accuracy. In order to enhance the efficiency and accuracy of the techniques used for water detection and plugging, an acoustic controlled pressure-balance switch has been developed.With an adaptive dynamic pressure balance system, piston valves in the switch can endure differential pressure up to 20 MPa during opening and closing processes.By means of remote acoustic controlled technique that transmits acoustic signals through tubing, the down-hole switch can be controlled remotely on the ground to facilitate production in different layers (in vertical wells) or in different intervals (in horizontal wells) according to operational requirements. Laboratory static pressure testing shows that the switch can withstand high temperature up to 125℃ and high pressure up to 50 MPa for 30 min with no leak or deformation.Differential pressure tests show that pressure balancing device can resist the differential pressure up to 25 MPa on the piston. Moreover, the electric motor can drive the piston to move reciprocally with no leak or seepage in dynamic sealing. Field tests show that valves can be opened or closed by the electric driving mechanism upon reception of instructions transmitted by acoustic waves from the ground by the receiver. It is considered that the switch can provide reliable technical support for enhancing recovery in the oil well.