Two dimensional flame temperature distributions in D.I. diesel engine with high pressure fuel injection were measured by the image analysis of high speed photographs based on two color method.Effects of injection pressure and nozzle hole diameter on flame temperature distribution were examined. The flame temperature in the case of high pressure injection is higher than that in low injection pressure. The higher flame temperature in high pressure injection results from the rapid compression of burned gases.The KL value which is an index of soot density in the combustion chamber decreases as injection pressure increases. The higher oxidation rate of soot at the later period of combustion may contribute to a soot reduction in the case of high pressure injection.