The utility model provides a high-strength and durable isolation device for power overhead line construction. The device comprises a first isolation mechanism, a second isolation mechanism and a low-voltage elastic line, the first isolation mechanism comprises a first main beam, a first hoop connected with the first main beam and a brake assembly arranged on the first main beam. The second isolation mechanism comprises a second main beam, a second hoop connected with the second main beam and a clamping piece arranged on the second main beam. The first isolation mechanism is fixed to a first electric pole through a first hoop. The second isolation mechanism is fixed on a second electric pole through a second hoop; one end of the low-voltage elastic wire is fixed on the clamping piece; whena new line is erected, the new line is hung on the low-voltage elastic line so as to be isolated and supported by the low-voltage elastic line, other lines cannot be affected, namely, the other linescannot be pulled apart, losses caused by construction are greatly reduced, meanwhile, the newly-erected line cannot be abraded, and the construction quality is guaranteed.