As a carrier of underwater acoustic equipment transmitter and receiver, transducer needs to be constantly measured, including of its impedance, phase angle, etc, for preparing the matching circuit, calculating electro-acoustic conversion efficiency. Impedance analyzer has a wide frequency range, high precision, but it has large volume, high price and other issues. It is also difficulty to carry. Therefore, this paper designed a small, impedance testing device which is easy to carry, and can be applied to me...