The invention discloses a method for optimally setting expressway traffic safety facilities, which comprises the following steps of: determining key sections of the optimally-set expressway traffic safety facilities; optimally setting the safety facilities of sharp bend, inflection and continuous curve road sections; optimally setting the safety facilities of a bridge head combined with a sharp curve section; optimally setting the safety facilities of a long and steep longitudinal slope section; optimally setting an emergency lane; optimally setting the safety facilities of a long straight line section; optimally setting the safety facilities of a poor sight distance section; optimally setting the safety facilities of roads and bridges, and roads and tunnels transition sections; and optimally setting the safety facilities of a vertical crossing section. In the method, requirements of a driver on safety, quickness, high efficiency and comfortableness are fully met according to the influence of road conditions such as a plane and vertical section line, a pavement structure, roadbed and side slopes, bridges and tunnels, an overhead crossing project of the expressway on driving safety.