Abstarct: In this thesis, the effect of adding hydrogen to the performance of gas engine 87 d will be discussed. For modeling AVL FIRE software due to the ability to model the combustion chamber with the injection of fuel is used. The baxse engine is an engine with power of 1000 kW round and 1500 rpm that to turn it into a gas engine needs to make changes to the basic engine including the injection system. It Seems to hydrogen as one of the best additives, can significantly reduce fuel consumption and harmful emissions in internal combustion engines. Therefore, in this research, the effect of adding different mass ratios of hydrogen fuel to natural gas fuel flint to see a change in behavior of flint fuel is examined. Hydrogen has wider flammability limits, higher flame speed and faster burning velocity which enable engines running on very lean mixtures. In this paper, the hydrogen mass ratio of 0, 0.002, up 0.014, which is equivalent to adding 50% of energy inner chamber entered And by examining the various aspects of performance and emissions, by considering these two views is determined that, 0.006 mass ratio of hydrogen which is equivalent to adding approximately 18% energy to the combustion chamber for this engine is the optimal point. Then the appropriate time for Engine optimization that is equivalent to 0.006 mass ratio is determined and according to the achieved results, 3 or 4 degree drop is suitable ignition timing for these mass ratio.