The experimental study was conducted against the fact of serious water resource shortage and secondary salinization in arid irrigation regions. Effect on maize root growth and soil water-salt dynamic in rootzone subjected to same drip irrigation quota was studied under three soil salt treatments. Under 0.2776 m3\5m -2 drip irrigation quota below plastic film, maize production was feasible when soil conductance rate was less than 1.575 ds\5m-1. The method of drip irrigation below film can effectively restrain the upward motivation of soil salt, leading to an obvious motivation of soil salt in 0\_40 cm layer with 7.0%, 9.5% and 23.0% of salinity decrease in QY1, QY2, and QY3 treatments than the check, resulting in the highest salinity in 40\_60 cm layer. The desalinated zone in 0\_40 cm soil layer is beneficial to the development of maize root system, 54%~91% of the total distribute within this soil volume. Furthermore, 67% of water was saved by drip irrigation below film over flooding, saying nothing of well-rounded technical system, self-produced materials internal, and decrease of cost, which indicated that drip irrigation below film could be widely extended in arid irrigation regions.