Abstract: The reaction of N<SUB<2</SUB<H<SUB<4</SUB< with F atom was predicted to have two reaction channels by the direct ab initio dynamics method.These channels were scanned at the UB3LYP/6-31+G(d,p) level and the energetic information was further refined by CCSD(T)/aug-cc-pVTZ method.The results revealed that the two equivalent channels(N<SUB<2</SUB<H<SUB<4</SUB<+F→N<SUB<2</SUB<H<SUB<3</SUB<+HF) occur synchronously via the formation of a pre-reaction complex with C<SUB<s</SUB< symmetry rather than via the direct H abstraction.Then it evolves into a hydrogen-bonding intermediate through a transition state with nearly no barrier and high exothermicity,whereas the intermediate decomposes into N<SUB<2</SUB<H<SUB<3</SUB< and HF finally.The rate constants of these channels at 200～(3?000?K) were calculated by ICVT/SCT method.