The navigation problem of multi-robot movement in a complex and unknown environment is studied in the paper. A new algorithm, ants navigation algorithm, is presented. At the start the method maps the global targets onto the area near the border of the robot’s eyeshot, and takes them as the local targets. Then two groups of ants will be cooperating to complete the search for the local optimal path in the robot’s eyeshot. Based on these configurations, the algorithm can predict possible collision with other robots and execute subsequent avoidance plans. The local search will be executed by the algorithm repetitively whenever the robot progresses a step. So, the path of the robot will be altered dynamically, which makes the robot move on the global optimal path to the ending node. The simulation results indicate that the optimal path, which the robot moves on, can lead the robot to reach the end safely even in complicated geographical environment. The effect is very satisfactory.