The mechanism of the reaction between the NH2 radical and fulminic acid (HCNO) to gain H2O or H is studied using computational quantum method, namely DFT (Density Functional Theory), the detail is B3L YP/6311++G(3df,2p). The potential energy surface (PES) indecated that there are five different reaction pathways which have been carried out. It shown that P4 (NCHN+H2O), P3 (H2O+HNCN) are the most favorable. The study also clarified more about the reaction mechanism of the NH2 radical with fulminic acid and in fact this reaction is one of the important ones in the atmosphere and combustion chemistry.