Abstract: In order to explore the effect of 250 g/L propiconazole EC on wheat stripe rust and powdery mildew and the reasonable application dosage, a field demonstration experiment was carried out through the method of forecast and investigation, randomized block design and statistical analysis. The results showed that during the spring wheat stripe rust epidemics, the two- time continuous application of 600 mL/hm2, 450 mL/hm2 and 300 mL/hm2 of 250 g/L propiconazole EC had a good control effect on wheat stripe rust. The control effects after 8 days and 18 days were still above 98% and the difference among different application dosages was not significant. Also there was a good control effect on wheat powdery mildew. After 8 days, the control effect could reach 100% but the effect could only be kept for about 10 days. After 18 days, the control effect of 250 g/L propiconazole EC significantly decreased, the effect of 600 mL/hm2 was only 78.4%, and the effect of 450mL/hm2 or lower was under 41% . In the case of not serious wheat stripe rust and powdery mildew, the optimal application dosage was 300-450 mL/hm2, which could reduce pesticide usage and pollution, and also save the control cost. Under heavy outbreak of powdery mildew and in the mixed incidence area of the two diseases, the 250 g/L propiconazole EC application should be 600 mL/hm2 for two times to ensure the control effect. There was no difference between 250 g/L propiconazole EC produced by Lier Chemical Co., Ltd. and Syngenta Suzhou crop protection Co., Ltd. in control effect with the same dosage, and the domestic production and foreign production did not differ in quality. For saving the cost of prevention and control , it is better to use 250 g/L propiconazole EC produced by Lier Chemical Co., Ltd.