Abstract: A series of novel 1, 3, 4-thiadiazole-thiourea compounds containing gem-dimethylcyclopropane ring 8a-8t were designed and synthesized by multi-step reactions in search of novel antifungal molecules. Structures of all target compounds were characterized by FT-IR, ¹H NMR, ¹³C NMR, ESI-MS and elemental analysis. The antifungal activities of the target compounds were preliminarily evaluated. The bioassay results revealed that, at 50 mg/L, the inhibitory rate of compound 8l(R=m-BrC₆H₄) against P.piricola was 79.5%, which was better than that of the positive control chlorothalonil. In order to design more effective antifungal compounds against P.piricola, analysis of the three-dimensional quantitative structure-activity relationship(3D-QSAR) was performed using the comparative molecular field analysis(CoMFA) method. The reasonable and effective 3D-QSAR model(r²=0.991, q²=0.514) was established.