In order to generate an antibody against a small hapten molecule, the hapten is cross-linked with carrier protein to make it immunogenic. In this study, the hapten (Fumonisin B 1, FB 1) was coupled to ovalbumin (OVA) and bovine serum albumin (BSA), respectively by a short cross-linker reagent (glutaraldehyde, GA). To develop a technique for detecting the conjugation, the hapten-protein conjugates (FB 1-OVA and FB 1-BSA) were characterized thoroughly by ultraviolet (UV) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), respectively. The molecular weights of FB 1-BSA and FB 1-OVA were 74,355.301 Da and 48,009.212 Da, respectively determined by the method of MALDI-TOF-MS. The molecular coupling ratios were 11 and 5 in FB 1-BSA and FB 1-OVA, respectively. In this experiment, MALDI-TOF-MS was selected as the most efficient method to evaluate the cross-linking effect and calculate the molecular coupling ratio.