Abstract: Taking the maximum oil recovery index as the object function, applying the concept of the proppant index, the new optimal design method of fracturing is studied. As for the low and ultra-low permeability oil reservoirs, the maximum production after pressure can only be obtained by laying the same emphasis on long seams and the relatively high dimensionless fracture conductivity. The new method can be applied to the exploration well fracturing transformation, the development well fracturing stimulated transformation, the optimal design of fracturing with fixed amount of proppant, and the selection of fracturing plans with different amount of proppant. Furthermore, it is easy in operation and has scientific and rational optimal results. The application of the new method can be a good reference to the fracturing transformation of low and ultra-low permeability oil reservoirs in the future.