In order to increase the hydrogen availability and understand the effects of premixed hydrogen on engine knock, a WP7.270 turbocharged 6-cylinder diesel engine was used as the research object and bench tests were carried out under different rotational speeds and loads based on the method of intake manifold hydrogen injection. The total mass of test fuel kept constant, the mass fraction of hydrogen increased until the engine knock occurred, and the test results were compared with the original data. The results show that the maximum displacement rate of hydrogen is 83%, the gas injection timing advances, the engine thermal efficiency increases by 7.7%, the in-cylinder peak pressure increases by 39.6%, and the CO₂, CO, HC and soot emissions reduce. The NO_x emissions increases, but reduces obviously at the load of 30%. The CO₂ emission is almost zero. In addition, the combustion is not stable.