Abstract: The paper provides 3 special external inspection techniques to detect the pipe wall thickness and pipe defects for buried pipelines in oilfield, that is, pulse transient evaluation method, long-spacing guided wave inspection method and spot check with ultrasonic wave inspection. Advantages and disadvantages of these techniques are analyzed and compared. Through application of these inspection techniques at Shengli Oilfield and abroad, applicable scope of these techniques is given, which has guiding significance for pipe corrosion and defect inspection in oilfields' pipeline and warning of pipeline leaking accident.