The present invention discloses a morphological filtering-based electrical imaging reservoir fracture and cave body quantitative characterization method and system. The method includes the following steps that: 1) noise suppression and blank band encryption interpolation are performed on original electric imaging logging data to obtain full-coverage rate electrical imaging logging data; 2) structural elements of appropriate shapes and scales are selected, and morphological filtering is performed on the obtained electrical imaging logging data in the step 1), so that fracture and cave pore distribution of different scales can be determined; and 3) the proportion of the porosity of fractures and the proportion of the porosity of corroded caves are calculated according to the fracture and cave pore distribution of different scales, so that a fracture and cave porosity spectrum which can indicate pore throat size and porosity distribution relationships can be obtained. According to the method of the invention, a mathematical morphological filtering method is introduced into imaging logging data processing; based on the filtering and anomaly recognition technologies of conductivity signals of different scales, the signal-to-noise ratio and identifiability of fracture and cave abnormal signals are improved; and exact information such as intuitive fracture and cave shapes and scale distribution can be provided for the processing and interpretation of electrical imaging logging data.