Under-mulch drip irrigation is an important irrigation method in irrigation agriculture of Xinjiang. However, soil salt accumulation induced by its slow deep leaching and brackish irrigation water is an urgent problem in development of sustainable agriculture. To explore characteristics of the salt distribution and accumulation in soils as affected by rate of under-mulch drip irrigation with brackish water, a field experiment was carried out in the Water-saving Irrigation Experiment Station of the Shihezi University. The experiment was designed to have three irrigation rate treatments, Treatment Q36: 3 150 m³ hm^-2, Q48: 4 200 m³ hm^-2 and Q60: 5 250 m³ hm^-2, and used water 3.32 g L^-1 in salinity. Analysis of soil samples taken before and after the irrigation indicated that the soil salinity in the root area demonstrated a basical declining trend at the forming stage of a wetted soil volume, and accumulation at the redistribution phase of soil water, while that in the soil under the root displayed an opposite way, rising in the former phase and falling in the latter. Analysis of salt distribution and balance in the soil profiles after harvest show that in Treatments Q36 and Q48, the input of salt with the irrigation stayed mainly in the 0~120 cm soil layer column, while in Treatment Q60, soil salinity increased significantly in the soil below 120 cm. Irrigation contributed about 21 percent of the increase. It was found that after 36 hours of irrigation, the wet front got into 80, 90 and 120 cm deep in Treatments Q36, Q48 and Q60, respectively. The water from the dripper infiltrated deep into the soil, bringing down salt into deep layers of the soil profile, which contributes positively to mitigating the problem of salt accumulation in the surface soil.