Abstract: Superfine cement plugging technology is an effective way to plug thief zone, to reduce water production and/or invalid water injection, and to improve oil displacement efficiency of injected water. After the formula and operation technologies of superfine cement plugging are improved, it can greatly improve the effectiveness of water plugging in Henan oilfield. When combined with acidiza-tion and reperforating measures, it can remarkable increase oil production while reduce water cut