A TGDI (turbocharged gasoline direct injection) engine is developed to realize both excellent fuel economy and high dynamic performance to guarantee fun-to-drive. In order to achieve this target, it is of great importance to develop a superior combustion system for the target engine. In this study, CFD simulation analysis, steady flow test and transparent engine test investigation are extensively conducted to ensure efficient and effective design. One dimensional thermodynamic simulation is firstly conducted to optimize controlling parameters for each representative engine operating condition, and the results serve as the input and boundary condition for the subsequent Three-dimensional CFD simulation. 3D CFD simulation is carried out to guide intake port design, which is then measured and verified on steady flow test bench. CFD simulation is also conducted to gain insight into in-cylinder flow, fuel-air mixture formation and combustion, and therefore, support the design of intake port, combustion chamber and piston crown. Transparent engine study is carried out under catalyst heating, part load, and full load conditions with several injector variants. Measurement data is analyzed in terms of combustion stability, combustion phasing, combustion duration, mixture formation and emission (HC/NOx/soot), and the best injector variant is selected based on this analysis. With the support from CFD simulation and experimental investigation, an optimized combustion system is efficiently developed and released for subsequent P&E (performance and emission) development.