Abstract: A high efficiency traffic sign includes a retroreflective film and a diffuser film. The retroreflective film is located between the body of the traffic sign and the diffuser film so as to form an indication face. The traffic sign is located higher than a road and the indication face faces coining vehicles on the road. A projection light source module is located on one side of the road and emits a light beam toward the traffic sign and the light beam covers the indication face. The light beam passes through the diffuser film and reaches retroreflective film. The light beam is then reflected and passes through the diffuser film again, the diffuser film changes the reflective path of the light beam which passes through the diffuser film to form a diversified light beam to allow the drivers of the coining vehicles on the road to see the traffic sign clearly.