Abstract: To rationally arrange the farmland irrigation of beer barley and optimize water resources allocation, we used the Penman-Monteith formula recommended by the Food and Agriculture Organization of the United Nations (FAO) and the meteorological observation data (such as temperature, sunshine and wind speed) in the Yongchang meteorological station in east Hexi region from 2013 to 2017, to calculate the daily water demand during the growing period of beer barley and analyze the water demand law, at the same time, to study the temporal and spatial variation characteristics of soil moisture with automatic soil moisture data. The results showed that the total water requirement during the whole growth period was 608.0 mm. The key periods of water demand were tillering stage, booting stage, milk ripening stage; booting-milk maturity was a period of big water demand. Most of the changes of soil water in development period were contrary to crop water demand trends. The overall trend of soil moisture vertical variation was that the soil moisture gradually increased with the soil depth from shallow to deep. The research results provide a reference for rational irrigation on beer barley.