Abstract: Analysis and testing on impurity samples got from pumping stations in Lanzhou-Chengdu-Chongqing Oil Product Pipeline shows that main compositions of the impurity are iron compound composed from rusts Origin of the pipeline impurity is investigated and experimental research on the corrosiveness of the oil products transported by the pipeline and producing law of the rust attached to pipe internal wall are carried. Results indicate that the corrosiveness of the pipeline is lower and the impurities mainly come from rust attached to the internal wall of the pipe and sediment left during pipeline construction. Based on research conclusion, some suggestions on impurity prevention during pipeline construction and operation are presented.