Abstract: Aimed at the characteristic of agricultural climate resource, distribution of rainfall and imbalance of water suply and water requirement in semi-arid areas of the Loess Plateau, based on the technology of harvested rainwater and project establishment, through the limit supplemental irrigation, the effect of maize yield increase which are generated by maize supplemental irrigation amount in different periods and technology of film plastic cover with soil was studied. Impacts of the supplemental irrigation of harvested rain water on the growth, water use efficiency and yield of maize were analyzed. Results show that combined with the different micro-irrigation model(drip irriation in this paper), the supplemental irrigation of harvested rainwater in key period of maize is very remarkable for increasing the yield and water use efficiency of maize in arid areas where surface water and groundwater are heavy scare. Results also show that the limited water supply in key period of water lack is high efficient. The research provides theory foundation for development of water-saving agriculture of supplemental irrigation of harvested rainwater in arid areas.