Abstract: There is remarkable difference of hydraulic characteristic of emitter between in subsurface drip irrigation (SDI) and in drip irrigation(DI). Emitters of SDI are closed by soil and their discharges are directly effected by the soil. Under the SDI condition, experiments on the effect of hydraulic characteristic of emitter were carried out with the following factors under observation: type, discharge, work pressure of emitter and initial soil moisture. Based on these orthogonal test, it was found that the discharge of emitter in soil will be 1/2～1/4 of that in air. Charges of emitter discharge in the soil are mainly effected by their emitter hydraulic and soil characteristics. A modified formula of emitter discharge was developed for the tested soil.