The invention discloses an electric transmission line visual monitoring and alarming system which comprises a scenery complementary power supply system and an on-site monitoring and early warning system. The on-site monitoring and early warning system comprises a plurality of cameras, a control module, a PCI, a public network communication module, an alarm signal output interface and an alarm apparatus. The control module comprises a CPU, a video decoder, a video encoder, an instruction analyzing/compiling module and an RS458 interface, wherein the video decoder, the video encoder, the instruction analyzing/compiling module and the RS458 interface are connected with the CPU. Each camera is used for obtaining on-site video images of an electric transmission line, and comprises an analog video speed dome camera, a pan-tilt and a video server, wherein the pan-tilt and the video server are installed on the analog video speed dome camera. The instruction analyzing/compiling module is connected with the public network communication module through the PCI, the public network communication module is in communication with a remote host through a wireless public network, the CPU is connected with the alarm apparatus through the alarm signal output interface, the CPU is connected with each pan-tilt through the RS458 interface, and the CPU is connected with each video server through the video decoder. By the adoption of the technology, the electric transmission line visual monitoring and alarming system is high in response speed, high in monitoring efficiency, and suitable for being generally popularized and applied in a power grid.