Traffic facilities, which are important auxiliary parts of underwater road tunnels, play an important role in ensuring the safe, efficient and energysaving operation of the tunnels. In the paper, the differences between the underwater road tunnels and mountaincrossing road tunnels are analyzed，the requirements for the arrangement of the traffic facilities (including ventilation facilities, illumination facilities, comprehensive monitoring facilities, emergency calling facilities, fire detection and alarming facilities, firefighting facilities, escape passage, drainage facilities, structural health monitoring facilities, power supply and distribution facilities, traffic safety facilities, etc.) of underwater road tunnels are summarized, and the key points in the design of the traffic facilities of underwater road tunnels constructed by drill and blast method, shield method, immersed tube method or cofferdam building method are also provided. 