Disclosed are a continuous casting and rolling device and a process for a composite plate. The device comprises a continuous casting machine body, two steel ladle rotary tables, a tundish mounting platform, two tundishes, two crystallizers, a composite area, a secondary cooling area, extrusion rollers, hold-down rollers, a flame cutting device, a descaling machine, a tension leveler and a continuous rolling unit, the two tundishes are mounted below the different steel ladle rotary tables through the tundish mounting platform, the crystallizers are disposed below the tundishes, the composite area is disposed below the two crystallizers, the extrusion rollers and the hold-down rollers are arranged below the composite area, the secondary cooling area is located below the hold-down rollers, and a horizontal outlet end of the secondary cooling area is sequentially connected with the tension leveler, the flame cutting device, the descaling machine and the continuous rolling unit. The continuous casting and rolling device and the process for the composite plate have the advantages that the width of a composite plate blank can be adjusted, continuous production can be achieved, the process is simple, costs are low, the efficiency is high, operation and controlling are convenient, and the like.