During oil production from several wells in Daqing, significant productivity decline was noticed. One of the reasons behind the productivity decline might be scale precipitation. The corrosion is very serious for scaling of the fifth injection wells. It brings enormous damage to oilfield and seriously influences the oilfield production and development. Based on the research of scaling of three different sections of injection wells, we clear the distribution of injection wells scaled and the source of injection water. Choose the representative scaling wells of three blocks and injection water sample, use modern instrument analysis method to analysis the composition of water and scale sample. According to the data analysis, to certain the components of the sample scale, put forward the main form of scaling mechanism, and provide a dependable basis for making effective measures of scale removal and prevention.