A lower vertical tail duct steering driving mechanism for a power line inspection unmanned airship comprises a lower vertical tail duct and a duct motor control module. The lower vertical tail duct is arranged in a fixed airfoil. The duct motor control module is connected with a brushless motor in the lower vertical tail duct through a power control line. The lower vertical tail duct steering driving mechanism has the beneficial effects that when the unmanned airship hovers in the air, the lower vertical tail duct steering driving mechanism can achieve 360-degree flexible steering of the airship, and the low-speed operability and turning performance of the airship are improved effectively.