Abstract: Forty-seven Cucurbita pepo germplasms were used as experimental materials, and the effects of powdery mildew on Cucurbita pepo germplasms were studied by using morphological investigation and seedling identification methods.The genetic diversity of the germplasms was preliminarily evaluated, in order to provide reference for the breeding of new resistant Cucurbita pepo varieties.The results showed that the diversity index of 27 qualities varied from 0.18 to 1.82,with an average value of 0.80,indicating rich genetic diversity.The diversity index of 15 quantitative traits varied from 1.04 to 1.32,with an average of 1.20.The diversity index of quantitative traits was higher than that of quality traits.Based on the disease index and membership function values, 34 highly resistant germplasm, 12 moderately resistant germplasm, and 1 susceptible germplasm were selected for evaluation.