This invention provides a supplementary lighting device for video surveillance security cameras, including a housing. A movable plate is slidably connected inside the housing. The bottom end of the movable plate, located on one side of two sets of slide rails, has through slots. A first fixed shaft is rotatably connected inside the housing, with one end of the first fixed shaft passing through a corresponding through slot and housing a camera. A second fixed shaft is rotatably connected inside the housing, with one end of the second fixed shaft passing through a corresponding through slot and housing a base plate. A supplementary light is installed on one side of the bottom end of the base plate. This invention uses an electric cylinder to drive the movable plate along the slide rails, and with the help of gear and rack transmission, the camera and supplementary light rotate synchronously around the first and second fixed shafts. This ensures that the supplementary lighting direction is always consistent with the rotation direction of the camera, avoiding problems such as reflections, shadows, or uneven lighting in the monitoring image, and meeting the real-time dynamic adjustment requirements in remote monitoring scenarios.