The adsorption and desorption behaviors of ammonia on TaC(0001) surface have been studied by employing spin-polarized density function theory calculations. The surface energy calculation results show that TaC (0001) terminating with Ta is the most stable surface. According to the optimized structural and energetic properties, it was found that NH3 prefers to adsorb on the top site, whereas NH2, H prefer to adsorb on the triple hcp site and NH, N prefer on the triple fcc site. In addition, three transition states were found for analyzing the mechanism of dehydrogenation of NH3, and the N recombination reaction was also considered. The results show that the desorption of nitrogen atoms is the rate-determining step in the overall reaction. Finally, in order to further elucidate the mechanism of NH3 adsorption and dissociation on the surface of Ta-TaC, the electronic structure of the most stable adsorption position was analyzed from the perspective of charge density distribution and electron density of states. The results of electronic structure calculation show that NH3 molecule is adsorbed on the surface through the mixture of 2PZ orbital of N atom and 5dZ2 orbital of substrate Ta. With the progress of dehydrogenation, the charge transfer phenomenon becomes more and more serious. The charge transfer between adsorbate and substrate plays an important role in accelerating NH3 dehydrogenation catalytic process.