A force sensing resistor (FSR) is a conductive polymer that exhibits a decrease in resistance due to an increase in the force applied to the active surface area. This paper aims to identify the characteristic operating region of the FSR integrated to e-textile structure. In this paper, the e-textile circuit including different conductive yarns with different linear resistance values, and FSR electrical interface that is composed of opamp circuit that can generate different loading profiles by different measuring resistor values were simultaneously designed to satisfy FSR integration to textile structure. In attempt to create FSR's operating region, different ranges of forces below 1 kgf were tested via FSR integrated to e-textile structure. Additionally, a mathematical model based on the results of experiments was created to build simulation of e-textile-based FSR's response as well as to characterize the relation between the measured voltage and force applied at FSR's surface. The system and proposed models are able to identify the applied force easily and can be embedded to textile structure for pressure detection.