The invention provides a fault karst body reservoir quantitative characterization method. The method comprises steps: the development mode of the fault karst body is built; with the development mode of the fault karst body as a guide, earthquake prediction on fault karst body characteristics is carried out; with a karst development mode as a guide, a fault karst body reservoir three-dimensional geological model is built; and based on production dynamic data, the fault karst body reservoir three-dimensional geological model is corrected. According to the fault karst body reservoir quantitativecharacterization method disclosed in the invention, the fault karst body reservoir development mode is thoroughly considered, based on geophysically-predicted fault karst body correlation attributes,a well-to-seismic integration geological modeling method is adopted, the distribution of a fault karst body outer contour, inner characteristics and attribute parameters is built respectively, the fault karst body reservoir characteristics are quantitatively characterized, and reliable basis is provided for reserves evaluation, numerical simulation and development program adjustment.