The machine oil enter the combustion chamber and combust caused by cylinder liner non-uniform distortion is an important factor which makes the diesel engine PM worsen. The 493-diesel was taken as an object to study. It was found in the study that the temperature around cylinder liners has been improved by the configure optimum of water jacket in order to reduce the cylinder liner distortion and PM emission. And validity of reducing PM by uniform the cylinder liner distortion has been verified. The test results proved that this method could reduce PM emission in-cylinder when the PM emission could not be reduced by using other in-cylinder cleaning ways.