Abstract: In this experiment, three typical beer barley yielded from different areas in Gansu Corridor were selected in order to determine its epiphytic microbial flora and the dominant microbe species.The results showed that the epiphytic bacteria colony count on barley was the largest, reached 106 ～ 107cfu/g;the yeast count was 104 ～ 105cfu/g;and the mould count was 103 ～ 105cfu/g, which vary greatly between different origins.Nine dominate strains of bacteria, nine dominate strains of yeasts and eleven dominate strains of moulds had been separated and identified from epiphytic micro bial flora of barley.It indicated that epiphytic microbial flora of barley had certain diversity, and there were some differences in microbial composition come from different origins.Enterobacter aerogenes, Staphylococcus chromogenes and some mould strains that probably produce mycotoxins were detected out from a few of samples.This inferred that there existed a biological safety problem.Therefore barley cleaning should be strengthened during malting, especially steeping stage so as to reduce the harmful pathogens carried by barley.