The invention discloses a secondary maintenance aviation plug safety extension device. The device comprises a bottom plate. Four universal wheels are arranged on the lower side of the bottom plate. Aplurality of pneumatic rods are arranged on the bottom plate. A panel is mounted at the tops of the pneumatic rods. The two sides of the panel are each rotationally connected with a side plate. A telescopic plate group is arranged on the front side of the bottom plate. The telescopic plate group is connected with an insulating plate mounted on the panel. A through hole is formed in the insulatingplate. A secondary extending line is installed in the through hole. A front inserting hole is formed in the front end of the panel. A sliding block is arranged in the front inserting hole in a slidingfit mode. The sliding block is connected with a connecting rod. A rotating shaft is arranged at the end of the connecting plate. The rotating shaft is connected with the insulating plate. According to the invention, while the secondary extension of the aviation plug is realized, the miniaturization and portable design of the whole device can be realized at the same time. The use cost of the device is reduced, and the popularization and application of the device can be facilitated.