A road traffic control system is applied to an intersection to control traffic and includes a light support, three traffic lights, a bracket, a number of indicators and a light controller. The light support is installed at one side of one lane at the intersection; the traffic lights are fixed on the light support and above the lane. The bracket is installed at one side of another lane at the intersection, and a number of stop lines are formed on the lane. The indicators are fixed on the bracket and above the stop lines to control traffic. The light controller controls to synchronously turn on or off the plurality of indicators and the traffic lights, and the indicators emit the same color light as the traffic lights.