To address issues such as high soot emissions and short regeneration intervals in crane-specific engines operating at low speed, experiment was combined with chemical kinetics to investigate the effects of different-flow-rate injectors on engine performance and soot emissions, and the formation pathways of PAHs were identified. The results show that the low-flow injectors reduce peak cylinder pressure and peak instantaneous heat release rate and prolong the combustion duration compared to the large-flow fuel injectors. The release of a large amount of heat reduces key PAHs intermediates such as A₂，A₂—，A₃，A₃—and A₂R₅, thereby lowering soot emissions. Additionally, the adoption of low-flow injector not only has a minimal impact on engine performance but also significantly reduces the emissions of soot. Within the operating conditions of cranes, when a low-flow injector is used, as the operating torque increases, the combination of delayed injection timing and lower injection pressure enables the engine to achieve high thermal efficiency and low soot emissions. This is beneficial for enhancing engine fuel economy and reducing costs associated with excessive carbon deposition.