Abstract: In order to improve the power performance of large-capacity megawatt-class hydrogen internal combustion engine for power generation and prevent the abnormal combustion such as preignition, flash back and detonation, detail analyses were conducted on the key technologies of hydrogen internal combustion engine from the aspects of hydrogen injection technology, combustion strategy and air-fuel ratio control strategy, exhaust gas recirculation technology, turbo-charging technology, hydrogen nozzle technology, and exhaust gas after-treatment technology. Results show that, for the large-capacity megawatt-class hydrogen internal combustion engine, the widely used technology of air intake injection at present has a disadvantage of a poor power performance of internal combustion engine, while through adopting the direct injection technology, the power performance can be improved and the risk of flash back can be reduced. The risk of detonation can be reduced with the application of lean mixture combustion, and the nitrogen oxide（NO_x） emission can be reduced with the application of a mature exhaust gas after-treatment technology by ammonia（NH₃）-selective catalytic reduction（SCR）.