In this paper, the influence of sulfur and ash fraction of lubricating oil on particle emissions was investigated via experimental works. Especially, we focus on the characterizations like size distribution, morphology and element composition in diesel particles. All of the research was done on a two-cylinder diesel engine under different load conditions. Five kinds of lubricating oils with different levels of sulfur and ash fraction were used in this study, among which a kind of 5W-30 (ACEA, C1) oil was used as baseline oil. Diesel primary particles were collected by thermophoretic system, and analyzed by transmission electron microscopy and energy dispersive X-ray spectrum technique, respectively. Conclusions drawn from the experiments indicate that the sulfur and ash change the primary particle emissions directly. The sulfur fraction in oil increases the amount of primary particles with small diameter, while ash fraction leads to more primary particles with large diameter and shift the size distribution to the large size area. Besides, the boundary of the primary particles shows ambiguous when uses oil with high sulfur fraction. The nanostructure analysis results show that compared with the baseline oil, both sulfur and ash influence the nanostructure of particles and lead to shorter fringes with higher tortuosity. The energy dispersive X-ray spectrum test results show that the concentration of Carbon decreases when using oils with high sulfur and ash concentration. Also in relative compare to baseline oil, more Phosphorous, Sulfur, and Oxygen elements were found, when the oil with higher sulfur and ash fraction was used.