Subsurface drip irrigation (SDI), which has a wide application prospect, is one of the high-efficiency water-saving irrigation techniques. Because the emitters are buried in the soil, the hydraulic characteristics of SDI subunit pipe network are often affected by soil physical properties, and the research present on these problems are inadequate. In the paper, laboratory tests were carried out to investigate the influencing factors of hydraulic factors under subsurface drip irrigation, the treatments included work stress (60, 100, 150, 200, 250, 300, 370 kPa), soil initial moisture contents (12%, 18%), and soil bulk densities (1.25, 1.40 g/cm3). In addition, the sensitivity was also analyzed. In this study, PLASSIM emitters and Heping emitters were used. The main results were as follows: The work pressure was the main factor that affected the emitter discharge in all three soil samples, and the SDI emitter discharge was larger under higher work pressure. Soil bulk density and initial soil water content could limit the discharge, especially in the sandy soil. Significant differences in the sensitivities of emitter discharges for different soil samples were obtained. The sensitivity was larger in the sandy soil, while it was smaller in the loamy soil and smallest in the clay soil. Three kinds of sensitive indicator of the PLASSIM emitter declined with the increase of work pressure, soil initial moisture content, and soil bulk density. The results obtained in this study could provide scientific instructions on irrigation program and efficient irrigation system.