Abstract: In view of water cut increases dramatically in Zhongerbei Ng5 unit in Gudao Oilfield, the reservoir conditions of this unit was simulated. The result obtained by means of single core flow experiment indicated that the favorable sealing characteristics and residual resistance factor were gained in high,middle, and low permeability core with the new silica gel plugging agent. The injection parameter was acquired from various slug sizes and concentration, and the laboratory result indicates that the sealing characteristic is gradually increased with aggrandizement of slug size and concentration. At the same time, stiffness of the plugging agent formed by small slug size and high concentration is stronger than that of big slug size and low concentration in the sealing characteristics and flushing resistance capability. Laboratory test conducted in a parallel core flow apparatus showed that the fractional flow rate of low permeability core increased from 10%to 70%, the result demonstrated that the plugging agent improved diffluent capability.