Abstract: Permeability especially effective permeability is one of the most important parameters in the development of oil field. Traditional methods are usually constrained by cost or precision, and generally require a specific set of processes. It would have great value if permeability can be computed in normal production process. A research is made on how to calculate permeability using the data of production and producing fluid level. For the elastic-driven non-saturated reservoir that has no edge and bottom water, or the energy of water is weak, a new method to calculate the current formation pressure and drainage radius first, then to calculate the effective permeability using plane radial flowing equation is provided, it is based on material balance rule and Darcy equation. An example is made on calculating the permeability of seven wells of Block N3 in Hailar basin using the new method. The permeability calculated by the new method is similar to the result of well test analysis,it shows the new method is reliable. A reliable value of permeability can be provided for designing development plan of new blocks, such as determining well pattern, well spacing, and production capacity, offering values of permeability in numerical reservoir simulation, it has a favorable application prospect.