Abstract: Based on the characteristics of oil reservoir in Shinan 21 well area, technology of weak gels for in-depth profile control was studied. Plugging capacity of weak gels was investigated in lab. Moreover, the various factors such as injection pore volume, injection rate, injection timing, injection depth and injection sequence on the recovery were also investigated in laboratory. The experiment indicates that the system has few effects on oleic permeability, which can improve profile heterogeneity effectively. Besides, enhanced recovery of unit volume reached the maximum when the injection pore volume was 0.3Vp and the inject-produc distance of weak gel reached 3:10. The smaller the injection rate of weak gel, the earlier the in-depth profiling, the larger the enhancement in oil recovery was. The recovery of the weak gel injecting in order stronger after weaker was larger than that in order weaker after stronger.