Barley seeds were coated by 5% Diniconazole ultramicro powder. This experiment is to research about its control effect to main diseases and effect to seedling growth of barley. The results showed that the seeds were treated by 1:400~500 of this chemical and seeds can improve emergence rate, seedling growth and dry and fresh weight of the plants. Its control effect to Helminthosporium.gramineum, Helminthosporium.sativum,and Ustilago.nuda of barley is 90.4%~88.7%、90.1%~91.8% and 100%~83% respectively. The yield was increased 16%~12%.