The invention discloses a traffic isolation fence with a vehicle speed pre-alarm function. The traffic isolation fence comprises an isolation unit uniformly arranged along a road, and a connecting mechanism connected with each isolation unit; the isolation unit comprises a substrate, and an insulating spacer erected above the substrate; each isolation unit along two sides of the isolation strips arranged along the road is respectively provided with a pre-alarm color zone extended along the road, and the substrate of each isolation unit is wrapped between two pre-alarm zones; each pre-alarm zone comprises at least one color track horizontally extended, the color track is formed by linking color spectrums, and each color spectrum includes red, orange, yellow, green, blue, indigo and purple blocks arranged along a horizontal direction. The traffic isolation fence is simple in structure and has the vehicle speed pre-alarm function, thus the speeding phenomenon can be effectively reduced and the traffic security is improved.