Derivaties of 1,2,4-triazole and 1,3,4-oxadiazole have a lot of biological activities such as antifungi, antibiotic, antivirus, antitumor, etc. Nineteen hetero-compounds have been synthesized. Their structures have been confirmed by elemental analysis and the spectra methods as UV, IR and NMR. In this study, we focus on the analysis the first defragments on the mass-spectra of some compounds which is derivaties of 1,3,4-oxadiazole and 1,2,4-triazole.