The effect of the addition of H-2 on combustion and emission characteristics of Cummins ISM370 diesel engine was investigated. The cylinder pressure and heat release rate were tested under 70% load with the addition of 6% H-2 to the engine. On this basis, AVL FIRE software was used to construct numerical model of the engine at 70% load with the addition of 6% H-2. The simulation results and experimental results were compared, and the results gave a good consistency. Whereby, the numerical model of Cummins ISM370 engine was verified. Moreover, simulated the pressure, heat release rate, NO emissions and particulate matter (PM) emissions at 70% load with the addition of H-2 from 6% to 20%, then analyzed the effect of the addition of different H-2 on combustion and emission characteristics of the engine. The results showed that the cylinder pressure and heat release rate first increased then decreased with the enhancement of H-2 addition, NO emissions increased, while PM emissions decreased. Both the pressure and heat release rate reached the maximum value at the addition of 17% H-2. Thus, this paper provided a method to investigate the effect of the addition of H-2 on the performance of diesel engine and how to get a best ratio of H-2 addition. (C) 2014 Elsevier Ltd. All rights reserved.