Most of the sandstone reservoirs contained a little clay, and water flooding technology would induce clay fines migration. The important factors causing clay fines migration included clay surface charge, double electric layers, clay mineralogy, exchangeable cation, water salinity, water film and so on. According to relative literature investigation, clay fines could start to dislodge from pore surface only when the retention concentration of pore surface clay fine was greater than critical retention concentration. Then Bedrikovetsky’s critical retention concentration function was deduced by this theory. Although clay swelling and fines migration all result in formation damage, fines migration was able to improve reservoir porosity and permeability heterogeneities, alternate wettability, plug high permeability path, enhance washing oil coefficient and reduce water-cut according to the theory of clay fines migration analysis. Therefore, fines migration under proper control was good for enhanced oil recovery.