Using ab initio method, the minimum energy conformations and net charge distribution have been studied for H,2,CN radical isomers formed by addition of a H atom (or an electron) to HCN (or HNC) molecule. Calculations show that there are three possible isomers, namely H,2,CN(Ⅰ), H,2,CN(Ⅱ) and H,2,CN(Ⅲ). The order of relative stability is (Ⅰ),>,(Ⅲ),>,(Ⅱ). From quantum chemical study and the estimations in thermochemistry for the reactions (1) and (2), the possible role of H,2,CN radicals in prebiotic organic synthesis has been discussed and it has been proposed that H,2,CN(Ⅲ) radical is an important intermediate to synthesize amino acids. The results, show that HNC is also an important product in the evolution chain of biomolecules under some special conditions, such as the electric discharge for atmosphere.