Abstract: In order to study the change laws of subsurface drip irrigation (SDI) emitter discharge, the experiment scheme was arranged based on uniform design with mix levels of three factors such as work pressure of emitter, soil bulk density and initial soil water content. The discharges of SDI emitter under various experimental schemes were obtained through weighing means by laboratory test system of SDI emitter discharge. The empirical formula for calculating SDI emitter discharge is established based on the test data. Analysis results show that discharge of SDI emitter is slightly biger at the beginning of irrigation, but then reduces and tends to be constant after 1～2 min when work pressure remains invariable. Therefore, SDI emitter discharge can be considered as a constant. Under the same work pressure, the discharge of SDI emitter is smaller of about 5%～20% than that of drip irrigation (DI) emitter. Work pressure is higher, the emitter discharges of both SDI and DI are closer. Work pressure is the decisive factor to hydraulic characteristics of SDI emitter. The influences of soil bulk density and initial soil water content on SDI emitter discharge are not remarkable.