| Recently, drip irrigation is one of the ways, which are water-saving irrigation; however, there are still many problems when the drip irrigation process is applied in the field. The unreasonable drip irrigation system will cause soil salinization, as well as water resources wasting and low water productivity. Thus, a suitable irrigation regulation is required urgently to improve water use efficiency and control the water and salt effectively in the cotton field.To figure out a suitable drip irrigation regulation for the under-film drip irrigation cotton farming, we conducted field experiments for three years at the Bazhou Irrigation Experimental Station. In the test area 6 irrigation quota groups were set (6000m3/hm2,5200m3/hm2,4500m3/hm2,3750m3/hm2,3000m3/hm2, 2250m3/hm2),4 kinds irrigation frequency (16times,12 times,8 times,6 times) and 2 kinds layouts of drip irrigation pipes (1 film-lpipe, lfilm-2pipe). According to the monitoring data about the salinity, the quality of irrigation water, the quantity of irrigation water, groundwater quality, soil nutrients, the eight main ions, meteorology and agronomic traits of cotton, and the analysis with statistical software DPS, finally, a suitable drip irrigation regulation of controlling the water and salt in soil for cotton growing in south Xinjiang was put forward. The main conclusions are as follows:(1) Both 1 film-lpipe and lfilm-2pipe, two irrigation methods, they had very limited depth for salt leaching; the maximum depth of salt accumulation was between 50cm～80cm, the width was between 40cm～70cm. The way of 1 film-1 pipe concentrated salt in 40cm～70cm around the pipe, which just laid between the inside row and outside row of cotton growing, thus it was adverse for cotton growing, and the imbalance of water supply led to the significant difference between inside row and outside row as well; while to the way of 1 film-2pipe, the distance was 30cm～50cm, and salt accumulated between the membranes and at the middle of membrane, which was helpful for the germination of cotton, and water supply was balanced, thus 1 film-2 pipe was better than 1 film-1 pipe both in water supply and salt discharge. The distribution of salt in soil after drip irrigation is ellipsoidal and this ellipsoid can be divided into three zones, namely dilute zone, salt accumulation zone, high salt accumulation zone. With the same irrigation frequency, the result of salt discharge of the larger irrigation quota is better than that of the smaller irrigation quota; while with the same irrigation quota, the result of salt discharge of the lower irrigation frequency is better than that of the higher irrigation frequency.(2) In the same condition of soil, with the high frequency and large amount irrigation quota, the cottons grew strong limbs while without few balls, the water produce efficiency and the yield were lower too; while with the low frequency and small amount irrigation quota, the cottons were short, but it had high water produce efficiency and moderate yield; with the low frequency and large amount irrigation quota, it is easy for the water percolating into deep layer of underground, causing the waste of water resources, and the water produce efficiency was quite lower; with the high frequency and small amount irrigation quota, it had higher water produce efficiency and more yield. According to comprehensive analysis, with the high frequency and small amount irrigation quota, it had higher water produce efficiency; thus, it is suitable to apply high frequency and proper quota irrigation for cotton growing.In a word, the way of 1 film-2pipe-4row, with the high frequency (12～16 times) and the small irrigation quota (3750～4500m3/hm2) is appropriate for the cotton under-film drip irrigation system in South Xinjiang.
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