Potato early blight leaves collected from Hebei, Inner Mongolia and Heilongjiang were separated by tis-sue separation. The strain was identified as Alternaria solani by spore morphology. In order to screen the fungicidesthat can effectively control potato early blight in different regions, the indoor toxicity of six fungicides to A. solani was determined by mycelial growth rate method. The results showed that among the six agents, 80% mancozeb WPand 30% cymoxanil WG had better antibacterial effect, and the EC₅₀ values were 4.20-10.77 mg/L and 3.02-17.45 mg/L, respectively. 72% chlorothalonil SC was the worst fungicide with EC₅₀ ranged from 550.91-1 888.40 mg/L.The virulence of the tested fungicides to the strains from different areas was different, and the more virulent fungi-cides were screened according to the strains from different areas. The results showed that 80% mancozeb WP and 30% cymoxanil WG were more virulent to the strains in Weichang area of Hebei Province; 80% mancozeb WP and 30% cymoxanil WG were more virulent to the strains in Inner Mongolia area; 80% mancozeb WP and 25% azoxys-trobin SC were more virulent to the strains in Qiqihaer area of Heilongjiang Province.