Abstract: The optimal trajectory selection system based on analytic hierarchy process (AHP) was designed，in order to plan optimal obstacle avoidance trajectory for intelligent vehicle in structured road． Firstly，cubic B-spline curve was employed as the planner to generate path with continuous curvature and controlled maximum curvature，based on which path sets were constructed．Secondly，in order to achieve quantitative expression of subjective and objective indicators，the AHP system for optimal path selection was constructed and the optimal path was selected，by considering smoothness and economic criteria as the criteria，path length，curvature sum，curvature change rate sum and distance from target point as sub-criteria． Then，cubic polynomial was used to represent the change of velocity relative to time，so as to satisfy the continuity of velocity，acceleration and acceleration derivative． Fi-nally，test scenarios were designed according to national standards to verify the stability of the method and the real- time performance of the algorithm． After 5 000 cycles of simulation test，the result shows that the algorithm has a good real-time performance． The probability of feasible trajectory planning within 0. 1 s is 94%，while within 0. 16 s it is 100%． The planned trajectory is convenient for vehicle tracking and the method has a high stability． The peak lateral error of real vehicle test is less than 0. 21 m，the peak speed error is less than 0. 42 m/s，and the av-erage speed error is less than 0. 11 m/s，which show an overall trend of convergence．

Key words: trajectory planning, analytic hierarchy process, cubic B-spline curve, structured road, intelligent vehicle, obstacle avoidance