In order to study the effect of work pressure and soil physical properties on the flow rate of the subsurface drip irrigation (SDI) emitter, the soil fractal feature under different gradations was analyzed using fractal theory. Uniform design method was applied and the following four factors were considered in the experiment: the fractal dimension of the soil particle-weight, work pressure of the emitter, soil bulk density, and initial soil water content. The results showed that the fractal dimension was significantly influenced by the soil clay content; the fractal dimension increased as the soil clay content increased. When the PLASSIM SDI emitter discharge was increased, the soil fractal dimension decreased; the finer the soil texture was, the smaller the emitter discharge became. By taking soil fractal dimension factor into account, the experimental empirical formula for estimating the SDI emitter discharge has preferable universality.