In order to clarify the characteristics of soot formation and oxidation in cylinder of diesel engine, it is necessary to diagnose accurately for combustion of in-cylinder. The past techniques for soot measurement have limitations in providing the characteristics of soot in a diesel engine, whereas, laser-based 2D imaging diagnostics have the potential to provide better temporally and spatially resolved measurements of the soot distribution.The technique using laser sheet beam has been applied to an optically accessible diesel engine for the quantitative measurement of soot. The results provide the information for reduction of soot from diesel engine. We used both LIS and LII techniques simultaneously in this study. The images of LIS and LII show the quantitative distribution of the soot concentration in an optically accessible diesel engine. In this study, several results were obtained by the simultaneous measurement of LIS and LII techniques. The diameter and number density of soot in combustion chamber of the test engine were obtained from ATDC 20 degrees to 110 degrees. The increase rate of soot diameter was about 40% between ATDC 20 degrees and 110 degrees. And the number density of soot decreased significantly between ATDC 40 degrees and 70 degrees.