Abstract: G6 fault block in GJ oilfield is a self-contained reservoir with low-medium permeability.At the beginning of development,the numerical simulation of reservoir was used to establish the correct production limitation during early waterflooding. On the process of production,many measures such as reservoir reforming and protection have been taken to improve the reservoir according to the characteristics of the reservoir.The development layer series were subdivided,so the flooding patterns were improved.The reservoir was in a high stable production period after waterflooding.The rate of oil production has been kept at 1.7%to 2.3%for 10 years in 12 years since the oilfield was developed;and the lifting rate of water cut has been controlled in about 3 percent. All the development technique indexes reaches or surpasses the values of theory prediction.