The technique of whole plasticfilm mulching in corn planting with double ridges and furrows on dryland before sowing has been failed to conserve sufficient soil moisture and use the autumn rain in the next spring. Field plot experiments were conducted for three years to test the techniques in three different film mulching times:autumn，early spring

and the time before sowing. Results showed that compared with the conventional film mulching cultivation(full mulching before sowing)

the autumn whole mulching of double ridges and the early spring whole mulching of double ridges increased the water content in 0-100 cm soil layer by 2.7%and 1.5%

respectively

and increased water storage in 1 m soil layer by 245-501 and 138-317 m3 / hm2

respectively. The techniques increased the average field rainfall use rate of 8.5%and 5.6%

respectively

and the corn water use efficiency of 5.54 and 2.88 kg/ (mm·hm2)

respectively. The techniques of the autumn and early spring whole mulching of double ridges are technical modes of high-efficiency rainwater use of corn in the arid and semiarid agricultural areas with elevation of below 2 300 m and annual precipitation of 350-500 mm. The best covering time is before the soil is frozen in late autumn (generally from the last or the middle ten days of October and the beginning of November) and when soil is melted in daytime and is frozen at night (generally in the early-middle of March).