The invention belongs to the technical field of transformer iron core lamination technology, and particularly provides a large-scale transformer iron core visual detection system comprising a rack, a bridge frame, a bridge frame clamping device, a four-degree-of-freedom manipulator and a grating scale. The bridge frame is slidably connected with the rack. The bridge frame clamping device is fixedly connected with the rack. The four-degree-of-freedom manipulator is slidably connected on the bridge frame. The grating scale is fixedly connected with the bridge frame. The lamination detection technology is automated so that the overall verticality and window width of the iron core can be rapidly and accurately detected, and the automation level of transformer equipment can be enhanced.