Abstract: Corrosion in the surface injection system of cross -linked polymer flooding is serious in Xiaermen oilfield of Henan oilfield. A series experimental studies shows that the main causes of corrosion are weld decay and acid corrosion of cross - linker itself. Inner corrosion prevention with T09 - 17 coating is performed in cross - linker tanks and pipelines larger than DN50 of the surface injection system, while aluminium - plastic composite pipes and ABS pipes are used as pipeline smaller than DN50. These measures successfully solve the problems of corrosion.