Shunbei fault-karst reservoir in Tarim Basin is a special type of carbonate reservoirs. The reservoir spaces are mainly formed by caves and fractures transformed by faulting. Due to reservoir spaces with complex structures， irregular shapes， and strong randomness of distribution， there are many uncertainties in the traditional delineation technology of fracture-cavity spaces based on static seismic data. The forward simulation method of numerical well testing is adopted to analyze the geological significance of different well test curves according to fracture-cavity space delineation results， and it is clear that the fault-karst reservoirs can be dynamically characterized based on well test analysis. A quantitative characterization method of reservoir spaces is proposed by correcting the threshold values of fracture-cavity delineation with dynamical numerical well test data. This method determines the shapes and reserve sizes of the reservoir spaces， and then selects a more accurate delineation models by combining well test interpretation，production characteristics analysis， and other research means and using the reservoir space knowledge with the dynamic correction to constrain the threshold values of the seismic attributes.