This paper proposes a road risk assessment(RRA) algorithm based on lane and obstacle information, including obstacle selection based on lane line equations and risk assessment based on time to collision (TTC). The algorithm can integrate the functions of collision warning and lane change risk assessment, and can be implemented on actual vehicles. RRA can provide collision warning for vehicles in the lane and also give lane-changing suggestions, and can conduct risk assessment of the lane to be changed according to the needs of lane changing. In addition, the alarm logic is designed, that is, when multiple risks appear at the same time, it is determined which HMI signal to prompt the driver. This method has been tested on the AEOLUS D53 vehicle, and the test results show that the system can effectively evaluate the driving risk.