Abstract: Formation permeability damage caused by different sizes of suspended particle in produced water is a very important job in oil fields. The diameter summit of porous of the sandstone in A’nan and Ha’nan oil fields of Erlian is 4.0~6.2μm according to the data of pressure mercury; the permeability damages aresimulated by its produced water containing different sizes of suspended particle through cores of A’nan, while 1/12 ≤ Df/Dp ≤ 1,the maximum damage data would be obtained, while Df/Dp ≥ 2/3,the damage is less serious, while Df/Dp ≤ 1/8, the damage is small; Meanwhile, referred to the domestic and foreign study and conclusion of match relation in the research field, specially, the "Bridging Rule"of 1/7 which is stricter than 1/3, the advice is given that the key region of suspended particle, which are disposed in produced water is 0.5~7.8μm in A’nan and Ha’nan Oilfield.