A new mixture formation and combustion process for reducing both emissions and fuel consumption has been developed, where the fuel impinges onto the impinging surface and spreads into the free space, named the OSKA process. A single cylinder engine particulate emission test was conducted with full flow dilution tunnel. The OSKA process shows lower TPM (total particulate matter) emission than the conventional DI diesel at the corresponding operating condition.ISF(insoluble fractions) and SOF(soluble organic fraction) are lower than DI diesel's. Correlation between SOF and THC of OSKA engine is, however different from that of conventional DI diesel. OSKA emits lower THC than conventional DI diesel does at the same SOF emission. This is because the wall quenching effect is smaller in OSKA than in conventional DI diesel.A NEW MIXTURE FORMATION and combustion technology, impinging diffusion one named OSKA, has been developed by the authors. The authors have reported the exhaust and performance characteristics of the OSKA system. The OSKA system has relatively low exhaust emission characteristics as well as low fuel consumption performance(1, 2 and 3). In the authors' previous report, however, the particulate matters emissions have not included.