Abstract: It is an advanced technique to clean internal rust and apply internal coating for operational pipeline. Based on the experiment, reserch and practical application, the author tells the important significance of such technique, explains the processes and technical requirements of surface preparation with sandjet and chemical cleaning methods, describes the characteristcs and apparatus of such coating methods as airflow spraying. pigging and rotational spraying by pulling etc, and briefs the scene about utilizing such technique of intcrnal coating on 7 pipelines with a total length of 6300m.