Abstract: In January 2007, water blending technology was applied in Yaotan Oilfield in full scale.In the early stage of application, the excessive water blending was caused by poor physical property of crude oil, dispersed distributed oil wells, low individual well production, short water-free oil production period, and increase of production water cut, which resulted in increase of daily fluid treatment in station and excessive oil sales, so that the normal production of oilfield was seriously influenced. Based on water blending theory and combined with oilfield practices, water blending technology has been applied in the oilfield by simplifying work flow, improving chemical feed method and making reasonable work system, and finally got good effects such as stable production, energy saving, cost reducing and better economic benefits.