With the application of mulched drip irrigation, soil salt distribution and variation features in agricultural fields are catching attentions year by year. In the 121 Regiment of the Xinjiang Production and Construction Corps (XPCC), Shihezi City, Xinjiang which is a typical area with mulched drip irrigation, soil salts in cotton fields were monitored for 4 consecutive years. The results showed that soil salts were continuously transferred away from the irrigation lines by the irrigation water. Horizontally, the salts gradually accumulated towards the bare soil between films, while vertically, they moved gradually towards deeper layers. Soil salt distribution in soil profiles changed from a wineglass shape (which was typical in wasteland and narrows down towards deeper soil layers) to a uniform vertical line with longer history of mulched drip irrigation. And this change was relatively pronounced from the 2nd to the 4th year of irrigation. After 4 years of irrigation, the soil at 140cm below surface began to be desalinized and after 5 years of irrigation soil salt content was at a point that crops could tolerate. Soil salt content decrease was mainly affected by the local irrigation regime. Irrigation, especially large amounts of irrigation, changed the natural distribution features of salts. With periodic irrigation, soil salt content during crop growth period was relatively low and total soil salt content displayed decreasing trends. Soil salt content decreased mainly at the seeding stage and the late blossing and boll-forming stages. Soil salt content in the 0~300cm layer also decreased gradually with longer history of drip irrigation. After about 10 years of irrigation, soil salt distributed in a modified form of a plumb line. For current drip irrigation regime, it was suggested that the irrigation amount for the blossing and boll-forming stages should be properly decreased to about 618mm in fields with an irrigation history of over 5 years. However, a relatively large amount of irrigation water should be maintained for the seedling stage.