Film mulching and water-saving irrigation are the main measures to cope with water resources shortage and increase crop water productivity in the arid region of Northwest China. In order to explore the comprehensive influence of film mulching and irrigation system on farmland water and heat condition and seed-maize growth and reveal the variation of farmland water consumption and water use efficiency, field experiments of seed-maize were conducted at Shiyanghe Experimental Station for Water-saving in Agriculture and Ecology of China Agricultural University in 2017. The experiments involved ten treatments, i.e., two levels of film mulching, full-mulching（M1）and non-mulching（M0）and five irrigation amount levels of drip irrigation, i.e., W1, W2, W3, W4 and W5, respectively 100%, 85%, 70%, 55% and 40% of the local traditional irrigation quota. Results showed that compared with non-mulching, film mulching can reduce soil evaporation and increase soil temperature in early stage, which resulted in higher growth rate of plant height and leaf area index, and reached their maximum values by 7~10d in advance, increased the yield of seed-maize by 6.5%~44.6% and the water use efficiency by 16.9%~50.4% under the same irrigation conditions. But film mulching can block rainfall infiltration. For example, when the rainfall was 32.4mm, the percentage of rainfall infiltration into the soil was 22.4% less than that of nonmulched treatment. Under the same film mulching condition, the consumption of soil water storage was increased with the decrease of irrigation amount, thus the soil water storage was increased with the increase of irrigation amount. The higher irrigation amount was, the higher the plant height, the LAI and the total dry biomass were, while the lower the water use efficiency was. The yield of W1 was the highest and that of W3 was the second under the condition of film mulching, and there was no significant difference between them. While for the water use efficiency, W5 was the highest and W3 was the second. The M1W3 treatment can keep higher maize yield with water use efficiency enhanced by 17.6% compared with that of M1W1. In conclusion, although field mulching may reduce the infiltration of rainfall, it can advance the growth period and reduce soil evaporation, which enhanced yield and saved water in the production of local seed-maize to some extent.