In the intelligent transportation systems, maybe the automatic navigation system is the most difficult problem. Many researchers try to find a way to carry out cruise assistance. This paper describes some new thoughts and algorithms for lane keeping and obstacle detection with a single view for cruise assistance. The system uses multi-threshold to extract the lane line. Then, the conic model is used to reconstruct them. Based on the image direction-fractal dimension and rotation, translation and magnification invariable central moment (RTM), it detects the obstacle in front in the same lane. At last, it uses Kalman filtering to track the obstacle. We have experimented the system with the algorithms on highway at 100km/h in Sichuan province and Chongqing city in China. The result shows that the algorithms can work perfectly.