A new system for studying electrical properties of cell suspension is presented, which is based on the piezoelectric pressure wave propagation (Piezo-PWP) method. Because of the introduction of ultrasound to the system, the biological effects of ultrasound must be considered. In the experiment, the most important impact of the ultrasound is the steady-state cavitation. Under the exposure to the ultrasound, diffuse double layers of tiny gas microbubbles and cells are deformed, and the tiny change of potential can be detected by the electrode. The changing procession of diffuse double layers and the interaction of microbubbles and cells are studied. The system includes three parts, the ultrasonic wave generator, the PWP experiment cavity and the signal receiver. The center frequency of the piezoelectric transducer is 1.7MHz. A low power intensity ultrasound is used in the experiment, so as not to injury cells. In the experiment, the absolute ethanol, the distilled water, the saline, the chicken blood serum, the chicken blood cell suspension, the chicken blood plasma and the fish egg suspension are used as samples. In the study, the model of the ultrasound propagation in the sample, is built up and analyzed, through which the procession of the ultrasound affecting the electrical properties of cell suspension is clear. According to experimental results of different samples, there are two reasons which result in changes of electrical properties of the cell suspension. One is that the mechanical wave makes the diffuse double layer of microbubble deformation. The other one is the deformation of the diffuse double layer of cells, caused by compression and stretching of the microbubble. The experimental results and the ultrasonic wave propagation model of the cell suspension, show that the system may be helpful to the research of the electrical properties of cell and mechanism of ultrasonic biological effect.