In order to suppress the knocking phenomenon of hybrid engine, a Computational Fluid Dynamics (CFD) model is established based on the ultra-high compression ratio hybrid engine. Bench tests are carried out to analyze the influence of engine subsystem and control parameters on knocking. The results show that rapid combustion can be achieved by increasing the inlet tumble ratio. Improving the machining accuracy of the combustion chamber can improve the consistency of combustion. Separate cooling of cylinder block and cylinder head can realize intelligent temperature regulation. The addition of a water baffle can reduce the temperature of the metal. For the maximum effective thermal efficiency point of the engine, reducing the pressure loss of the Exhaust Gas Recirculation (EGR) system can make the EGR rate reach 25%. In high-temperature environments, the effective compression ratio and engine outlet temperature require precise control.