In order to improve the particle spatial distribution, promote the mixing of oil and gas, and enhance airflow movement in a combustion chamber, a swirl chamber combustion system in direct injection diesel was investigated. The mixture formation and combustion progress in the combustion chamber were simulated, including different nozzle hole cone angles with 146°, 150° and 154°. The results showed that in view of the fuel/air equivalence ratio distribution, the uniformity of mixture on nozzle hole cone angle of 146°was better than others. The combustion swirl and anti-squish swirl have effect on temperature distribution in the combustion chamber. NO emission was lowest with nozzle hole cone angle of 154°, while soot emission was lowest with nozzle hole cone angle of 146°. The emission performance was better than others with nozzle hole cone angle of 150°.