This paper attempts to theoretically analyze the tension and pressure decay of a single layer tubular elastic fabric used for pressure garments. In the theoretical analysis, we assume that the exponential decay model of the fabric tube on pressure and tension is used and supported by the experiment. We also reveal that in the experiment, the relative rates of pressure change and tension change of a fabric tube are the same no matter which reduction percent is used for making up the pressure garment. The model in this study could assist medical practitioners in providing effective clinical treatment with pressure garments for patients.