The fracture-cavity reservoirs have many types of reservoir spaces，large differences in pore，fracture，and karst cave sizes，and are macroscopically characterized by coupling of multiple flow patterns. The reservoir and permeability conditions and development models are very different from those of clastic sandstone reservoirs. Considering the special geological conditions and flow patterns of fracture-cavity reservoirs，and based on the classic fluid potential theory，the theoretical model of development fluid potential for different reservoir types and different development stages of fracture-cavity reservoirs is established. It also explains the calculation methods of potential energy，pressure energy，kinetic energy，interface energy and viscous energy in the mathematical model of fluid potential. Based on this，the improved streamline method is used to develop the numerical simulation program for the development fluid potential of fracture-cavity reservoirs. Research on the control effect of fracture-cavity reservoirs in Tahe Oilfield shows that the control method based on calculation of fluid potential is suitable for the three types of karst backgrounds：fault-controlled karst，weathered shell karst and composite karst. The production strength is greater，and the effect of fluid potential control in fracture-cavity reservoirs is better when the water body multiple is less than 10 times and the liquid production ratio is 4-6.