A cab roof structure, a cab and a rail train are described. The cab roof structure comprises: at least one roof connecting beam disposed on a roof carline; and at least two aluminum honeycomb panels, one roof connecting beam is disposed between every two aluminum honeycomb panels, and each aluminum honeycomb panel is fixedly connected to a left or right side of the roof connecting beam. The cab roof structure has the advantages of high structural strength, light weight, less welding and good manufacturability.