In view of the problem that the traditional free radical polymerization initiation method is difficult to realize the reaction control of in-situ polymerization plugging system in the reservoir，an atom transfer radical（ARGET ATRP）initiation system was developed to replace the traditional initiator. The effects of the amount of each component including the initiator 1， 2-dibromoethane，the catalyst ferric chloride，and the complex reducing agent vitamin C on the gelation time in the ARGET ATRP initiation system were investigated. The optimal ARGET ATRP initiation system was used to evaluate the injectability and plugging properties of the in-situ polymerization gel system in the core. Experiments showed that，under the condition of 80℃，when the dosage of 1，2-dibromoethane was 0.35%—0.4%，the dosage of ferric chloride was 0.012%—0.02%，and the dosage of vitamin C was 0.18%—0.26%，the dosage of each component could be adjusted to make the gelation time of the in-situ polymerization gel system greater than 24 h，and the gel strength reached I level. When the salinity was less than 7000 mg/L，the gelation time was prolonged with the increase of salinity，while the gel strength was reduced from I level to E level. The core evaluation experiment showed that the in-situ polymerization system had good injectivity. The ARGET ATRP initiation system could initiate the cross-linking of the polymerized monomers in the core，and the overall plugging rate of the core after the gelation reached up to 77.71%. It is feasible to use the ARGET ATRP initiation system to control the gelling time of in-situ polymerization plugging system.