A series of novel 1,3,4-thiadiazole derivatives bearing 1,2,4-triazolo[1,5-a]pyrimidine moiety were synthesized by the method of splicing active substructures. Among these derivatives, compounds 12, 13, 15-22 and 24-31 were firstly reported. All the compounds were assayed for antimicrobial activities against five fungi strains and four bacteria strains. The preliminary results indicated that compounds 25 and 28-31 showed good antifungal activities against Physaclospora piricola and Rhizoctonia solani. Compound 26 exhibited good antifungal activities against Cercospora beticola and R. solani. Most of the compounds showed better antibacterial activities against Gram-negative bacteria strains than Gram-positive bacteria strains. Compounds 25 and 28 showed the best activities against Pseudomonas fluorescence while compounds 30-31 showed good activities against Escherichia coli.