Abstract: In order to meet the requirement of high pressure common rail injection system equipped in diesel engine, the parameter designing of combustion chamber for common rail diesel engine is explored. According to the demand of high pressure injection to combustion chamber, the structural design factors of combustion chamber are briefly analyzed, including penetration distance, compression ratio, aperture ratio and bore depth ratio. The ranges of these parameters are given and the matching design process of combustion chamber is provided. The combustion chambers with different structures for 493 diesel engine has been designed and air flow field of combustion chamber has been analyzed based on combustion model by FIRE software. Experiments of combustion chamber with different parameters have been implemented on diesel engine bench and the experimental results show that the chamber with the structure of six holes and large diameter shallow bottom is more reasonable for this type of diesel engine.