Abstract: Since Fault 10 in Xiliu Huabei Oilfield is featured by high temperature, middle porosity and low permeability, a high-temperature gel deep profile controlling agent with the modified phenol-formaldehyde resin as cross-linkage agent is studied on the basis of reservoir characteristics. The basic recipe is determined through the laboratory experimental study, and the influence of polymer, cross-linking agent, aid cross-linking agent and de-oxygen agent usage on gel viscosity and gelling time are observed and studied. The results indicate that the formula of gel is adapt to reservoirs with temperature at 120 ℃, and has the advantages of good heat stability. The initial gel viscosity is lower than 100 mPa·s and the gelling viscosity is higher than 14Pa.s.The deep modified profile agent has been used in Fault 10 Xiliu and good effect has been obtained.