Abstract: In ±800 kV DC overhead transmission line project, the effect of wire tension insulator string’s load to wire sag and tension cannot be ignored in the continuous span because the string is longer and heavier than those of low voltage level. The stringing methods of ±800 kV DC transmission line are described briefly. By using moment balance principle, the relationship among conductor load, conductor sag and tension in the continuous span is analyzed. In both long continuous span strain section and Tension-Tangent-Tension strain section, analysis results prove effectiveness of proposed calculation method and treatment measures of tension tower adjacent span’s conductor sag. The result is also verified in engineering practice.