Abstract: Dimensionless pore volume technology has been used for improving the result of water injection. The dimensionless pore volume technology and traditional kh method were used to calculate the suitable production rate and injection rate in Gao 30 fault block oil reservoir. Meanwhile, through numerical simulation, the water flooding performance has been predicted by the two methods. The results indicate that the dimensionless pore volume technology is better than the traditional kh method, with the effective production period prolonged by 27 years, oil recovery increased by 5.48%, from 22.46% to 27.94%, and 19.88×10⁴t additional oil might be increased. Compare with the traditional kh method, the forecast results with dimensionless pore volume technology is accorded with the actual reservoir conditions, extending the effective production year, and improving the final oil recovery. This method can provide some references to calculate the suitable production and injection rate for the similar water flooded reservoirs.