| A cotton field experiment under mulched drip irrigation was carried out in order to study the effects of
different irigation frequency on soil water salt transport and distribution, and to evaluate different irrigation frequencies efficiency in preserving moisture ，controlling soil salinization, and increasing cotton yield. The results show that the soil moisture contents are not the same under different irrigation frequencies with fresh water at 375 mm，namely, low fre-quent irigation (10 days) and middle frequent irmigation (7 days) can all make the moisture suitable in soil layers of 0~60 cm，and the moisture content is the highest under low frequent irigation. Contrarily， the soil layers are in light -de-gree drought condition during flowering and boll fomming stage under high frequent irmigation (3 days) . Based on compre-hensive analysis on salinization or desalinization status of root zone under film and un mulched soil, low frequent irriga-tion is slightly better than high frequent irrigation and much better than middle frequent irigation. The irrigation frequen-cy has significant influence on cotton yield, and the highest yield can be obtained under high frequent irigation. |