Abstract: Rainwater utilization is a growth point of agricultural development in arid and semi-arid areas. Based on the characteristic of natural precipitation, distributing trait of farmland, agricultural planting system and law of crop requiring water and dynamic variety of soil moisture in arid and semi-arid areas, this paper put forward mobile rainwater collection on slope and irrigation system, in which crop is growing on slope-land in spring, the film is covered for collecting rainwater in autumn, the vaults are built in side of land for storing water and crop is irrigated lower land. At the same time, study was carried out about rainwater collection efficiency, moisture effect of farmland and production of system. The result indicates that this system has the merit of high rainwater collection efficiency, conserving soil moisture well and obvious increase production effect. It is a good rainwater-using mode that is fit for arid and semi-arid area.