Abstract: Based on the combustion characteristics of hydrogen in the internal combustion engine cylinder, the generation mechanism of NOx in the combustion process of hydrogen-based internal combustion engine was analyzed. The NOx generation and emission control were analyzed by controlling the air-fuel ratio, EGR, ignition advance angle and catalytic conversion. Meanwhile, the control of residual hydrogen in exhaust gas and other pollutants produced by engine oil combustion are analyzed, and the emission control route of hydrogen engine is proposed. The EGR+DOC（TWC）+DPF+SCR route of hydrogen engine is analyzed. The EGR+DOC+SCR route and EGR+TWC route of hydrogen combustion engine are analyzed, and the feasibility of related emission control route is discussed, which can provide ideas for future industrialization of hydrogen combustion engine.