Abstract: External Casing Packer is used in Shengli Oilfield in the high pressure well, leakage well, complicated well, multiple pressure layer cementing and completion well process,and solve the technical problems to ensure cementing quality. With the development of complex reservoirs and special process completion, by analyzing the existing problems, improving the structure, new External Casing Packers are researched and developed, improved sealing effect, meet the needs of special completion sequence. Aim at the more complex reservoir and diverse completion methods, should study the new structure and special features packer, to meet the needs of exploration and development.