Abstract: It is in detail introduced to the cause of forming scale in the oil-well and pipeline and the principle of preventing scale. According to the scale of the pipeline in Jianghe of Henan oilfield, the cheaper and more effective scale remover has been confirmed by the way of the scientific research and experiment in 3 years. The operation skills were also confirmed and the injection sequence of the diposal liquid was made out. Good affects, such as increasing oil, preventing scale and postponing the period of checking the pump, have been acquired. These experiments can provide direction of the preventing scale to Henan oilfield and the others.