This paper proposes a mathematical model of a pressure-sensitive conductive fabric sensor, which adopts the technique of electrical impedance tomography (EIT) with a composite fabric being capable of changing its effective electrical property due to an applied pressure. We model the composite fabric from an electrically conductive yarn and a sponge-like non-conductive fabric with high pore density, and the conductive yarn is woven in a wavy pattern to possess a pressure-sensitive conductive property, in the sense of homogenization theory. We use a simplified version of EIT technique to image the pressure distribution associated with the conductivity perturbation. A mathematical ground for the effective conductivity in one-direction is provided. We conduct an experiment to test the feasibility of the proposed pressure sensor.