On the basis of X-ray diffraction of clay minerals, analysis of resin-cast thin sections of cores, and scanning electron microscope (SEM) observation of samples in central Sichuan Basin, this paper studies the microscopic characteristics and occurrences of chlorite and the relationship between its genesis and reservoir development. The chlorite content in the study area is positively related to porosity and permeability. The distribution and occurrence of chlorite plays an important role in affecting the porosity and permeability of reservoirs.