Under-plastic-mulch drip irrigation was studied through field experiments in arid areas of Xinjiang in 2009.The influences of various irriga-tion quotas and frequencies on water-salt distribution and cotton growth were analyzed.The results show that irrigations with a cycle of 5days achieved the most appropriate moisture condition for cotton growth.With same irrigation quota,soil moisture increased by shortening irrigation cycle time.The higher irrigation frequency effectively reduced the salinity of root area.The treatment of 10 day cycle introduced fluctuations of salinity in soil and resulted in salt accumulation at the growth period.Considering water conservation,yield enhancement and soil salt reduction,the irrigation quota of 3900m³/hm² with a irrigation cycle of five to seven days are desirable for agricultural industry in the study area.