The invention discloses an ultra-high voltage transmission line channel hidden danger early warning method based on an SSIM algorithm. Obtaining a reference picture and a to-be-detected picture of thepower transmission line channel, wherein the reference picture is a normal picture when the power transmission line channel has no hidden danger, the to-be-detected picture is a picture which is shotat regular time and has the same power transmission line channel position, a difference graph of the reference picture and the to-be-detected picture is obtained through structural similarity SSIM algorithm comparison, and the hidden danger of the power transmission line channel is identified according to the difference graph. According to the method, the intelligent level of real-time video visual inspection can be improved, the burden of workers is reduced, the difference part is found out by comparing the pictures captured in real time with the reference picture, picture labeling is carried out, and recognition of the hidden danger of the ultra-high voltage power transmission channel is achieved.