Abstract: Currently the error of the method to determine chemical profile modification and treatment radius is big,and it does not fulfill the field requirement.So research is conducted to simulate the seepage characteristics and the distribution pattern of profile modification agents in heterogeneous oil reservoirs.Then the relationship between the treatment radius and the amplification of ultimate recovery is derived,that is,the amplification reaches the highest when the treatment radius is 0.18~0.24 times of well spacing.Pilot test is carried out in Xinjiang L Oilfield and the treatment radius is defined as 0.2 times of well spacing.Good effect is achieved.The research result may be a good reference to the profile control of injection wells.