The molecular recognition of β-cyclodextrin to 3-nitro-1,2,4-triazole-5-one (NTO) and 1,2-dihydro-3H-1,2,4-triazole-3-one (TO) was respectively studied by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The effects of different matrixes and concentrations on mass spectra were investigated. The results show that β-cyclodextrin has strong recognition ability to NTO and TO. While the mole ratio of sinapic acid used as matrix and complex was 100：1,the hydropeaks of the two kinds of complex used as base peak were determined by MALDI-TOF-MS,so that the molecular weights of TO and NTO were accurately obtained.