The analysis samples were taken from three different oilfields in Shengli oilfield. By using high magnification scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM),  the research of nanoscale observation and analysis of reservoir pore structure and pore-throat configuration relationships were conducted. The results show that the nanoscale pore and throat really exist in clastic reservoir and there are various pore types, and they can also be divided into primary pores and secondary pores. The nanoscale primary pores include five types, that is, single crystal layer seams, mineral cleavage joints, intracrystalline pores, intergranular pores and intercrystalline joints.