An intelligent road warning system based on an unmanned aerial vehicle comprises the unmanned aerial vehicle, a warning device, a driving device, a wireless device, an accumulator and a processor. The unmanned aerial vehicle is further provided with a first camera, and the first camera is arranged on the lower portion of the unmanned aerial vehicle. The warning device comprises a shell, a second camera, a display screen and a radar sensor. A passive reflector made of a reflective material is arranged on the outer surface of the shell. The second camera is arranged on the upper portion of the shell. The periphery of the display screen is wrapped with the shell. A radar detecting device is arranged on the lower portion of the shell. A connecting device comprises a connecting buckle, a connecting rope and a fixing buckle; the connecting buckle is arranged on the lower portion of the unmanned aerial vehicle; the connecting rope is arranged inside the fixing buckle, connected with the connecting buckle and the fixing buckle and pulled out from the interior of the fixing buckle when used; and the fixing buckle is arranged on the upper portion of the shell. The driving device comprises a driving motor and driving rollers, wherein the driving motor is arranged inside the lower portion of the shell, and the rollers are arranged on the lower portion of the shell.