Abstract: Hexaconazole-resistant strains of Sphaerotheca fuliginea were obtained by chemical taming and UV irradiation in the laboratory.The resistance factor of the resistant strain was 105 fold,while the sporulation capacity and pathogenicity were higher than their parent strains without significant difference.Hexaconazole-resistant strains exhibited no cross-resistance to tebuconazole,myclobutanil,polyoxin and azoxystrobin,but showed positive resistance to kresoxim-methyl.The results suggested that S.fuliginea may develop resistance to hexaconazole when it was used to control cucumber powdery mildew in the field.