The invention provides a seed treatment method for preventing and treating cucurbita pepo L. seedling rot and belongs to the technical field of agriculture. The method comprises the steps: firstly sterilizing seeds; then utilizing 14 kinds of traditional Chinese medicinal materials of radix pulsatillae, radix euphorbiae lantu, radix isatidis, folium isatidis, herba portulacae, radix scutellariae, szechwan sida herb, herba scuteliariae barbatae, Tibet lancea herb, osmanthus yunnanensis bark, suchow mosla herb, cleistocalyx operculatus leaf, Chinese tallow leaf and rabdosia eriocalys rhizome to soak the seeds; finally utilizing medicament chitosan oligosaccharide, fulvic acid, uniconazole, ABT rooting powder, propamocarb hydrochloride, glycine betaine, chitosan, pinolene and metalaxyl to perform seed dressing. The method disclosed by the invention can prevent varieties of diseases and insects of the cucurbita pepo L., especially has a very good preventing and effect on cucurbita pepo L. seedling rot, further has effects of resisting adverseness and strengthening seedlings and greatly improves yield and quality of the cucurbita pepo L.; meanwhile, the method delays plant drug resistance generation, reduces use amount and use times of pesticide and reduces agricultural cost; furthermore, pesticide residue amount is extremely low, and environmental friendliness is facilitated.