The invention provides an online monitoring camera for forest fire along a power transmission line. The online monitoring camera comprises an analysis module (1), wherein the signal interface of the analysis module (1) is connected with a cloud stage (3); the cloud stage (3) is respectively connected with an infrared lens (4) and a visible light lens (2) through two signal interfaces of the cloud stage; the monitoring camera obtains a temperature pattern by utilizing the infrared lens (4) and transmits the temperature pattern to the analysis module (1), the analysis module (1) judges whether a fire point is formed or not according to the temperature, and if the fire point is formed, the visible light lens automatically focuses, shoots a scene picture and transmits the scene picture through a video line. Therefore the online monitoring camera disclosed by the invention has the advantages that (1) the problem of monitoring the forest fire along the power transmission line in real time is solved; (2) the labor and the materials are saved for the prevention and reduction of natural disasters of the power transmission line; and (3) important information guidance can be provided for the prevention and the reduction of natural disasters of the power transmission line.