The present invention discloses an intelligent traffic safety pre-warning method, a cloud server, onboard-terminals and a system. The method comprises: a step (101): the onboard-terminal establishes a communication connection with the cloud server; a step (102): the onboard-terminal acquires data, and uploads data calculated based on the acquired data to the cloud server; a step (103): the onboard-terminal receives feedbacks from the cloud server, the feedback comprising the probability that the current vehicle has an accident within a set range of the current road segment; and a step (104): the onboard-terminal receives the probability that the current vehicle has an accident within the set range of the current road segment, and then transmits the feedback to the driver by human-computer interaction. The method, the cloud server, the onboard-terminals and the system fill in the gaps in traffic safety, danger pre-warning, and low visibility driving safety guarantee in rain, fog and the like in the traffic field, and ensure that the driving behavior is safer.