A roadside service unit, a traffic prompt device, a traffic prompt system and a traffic prompt method, relating to a field of computer technology, in particular to a field of vehicle networking and intelligent transportation technologies. The roadside service unit includes: a roadside acquisition device configured to provide traffic data; a roadside computing device communicatively connected with the roadside acquisition device, and configured to generate traffic prompt information according to the traffic data provided by the roadside acquisition device; and a roadside communication device communicatively connected with the roadside computing device, and configured to send the traffic prompt information generated by the roadside computing device to a preset area.