The invention provides a helicopter's power transmission line inspection tour device and an inspection method based on the device, which relate to the technical field of power transmission line inspections and aim to solve the problem that in the helicopter used inspections, only local images about the power transmission lines could be acquired which means there might be missed inspections. The three sets of image acquisition devices are referred to as a first image acquisition device, a second image acquisition device and a third image acquisition device. The control device is used to control the tower head images acquired by the first image acquisition device, the overall images of the iron towers acquired by the second image acquisition device and the power transmission line images acquired by the third image acquisition device. After the helicopter flies a circle around a power transmission line, the overall information of the power transmission line can be all acquired. Since all-around information could be acquired, high acquisition efficiency is achieved, making the device and the method suitable for the inspections of the power transmission line.