During the last few decades, concerns have grown on the negative effects that diesel particulate matter has on health. Because of this, particulate emissions were subjected to restrictions and various emission-reduction technologies were developed. It is ironic that some of these technologies led to reductions in the legislated total particulate mass while neglecting the number of particles. Focusing on the mass is not necessarily correct, because it might well be that not the mass but the number of particles and the characteristics of them (size, composition) have a higher impact on health. During the diesel engine combustion process, soot particles are produced which is very harmful for the atmosphere. Particulate matter is composed of much organic and inorganic composition which was analyzed after the optimization of SCR and EGR engine out. The combustion strategy is different in both the technologies so detailed analysis was done for both the combustion parameter to understand the behaviour of particulate matter with and without after treatment. The experimental study shows the detailed of particulate matter and soot formation and its general effects within the engine as well as other issues including filtration or removal, effects on the lubricant, engine design and operation and technologies related to soot contamination. The current trend in diesel engine emissions control involves multi-injection combustion strategies which are transforming the picture of diesel combustion rapidly into a series of low temperature, stratified charge, premixed combustion events where NOx formation is avoided because of low temperature and soot formation is avoided by leaning the mixture or increasing air entrainment prior to ignition. Keywords: Diesel engines; Soot; Particulate; emissions etc.