Aiming at the problems of poor physical properties，high water injection pressure，increasing number of under-injected wells year by year and difficult treatment in Jiyuan oilfield，combining with the flow characteristics of small water volume and branched form in Changqing oilfield，a long-term on-line injection enhancement technology based on boosting water injection and medicament pressure control was proposed after analyzing characteristics of main blocks. Different types of booster devices with water injection capacity of 100—300 m³/d were installed in the well site，and comprehensive depressurization and injection agents were added to meet the demand of water injection. The pressure prediction chart of main blocks was established and applied in Jiyuan oilfield. The results showed that the booster met the local on-line boosting and injection requirements. The comprehensive agent COA-2 for water injection wells with stripping dispersant，chelating agent，wetting agent，cleaning agent，acidizing corrosion inhibitor and methanol as the main agents，had the advantages of anti-swelling，scale inhibition and reducing oil-water interfacial tension，and good effect of pressure control and injection boosting. The pressure prediction chart of the main block provided a basis for effectively controlling the rise of pressure. A total of 48 well groups were implemented in the oil production plant，which improved the under-injection problem of 105 wells with ineffective multi-round injection stimulation. The average validity period was 266 days，the average single well daily injection increased by 11 m³，and the cumulative injection amount increased by 54.95×10⁴ m³. In the corresponding 826 oil wells，234 oil wells were effective with 2.25 t daily oil increase for average single well group，and 1.95 × 10⁴ t cumulative oil increase，which reached the purpose of long-term stable water injection for multi-rounds ineffective injection wells.