Abstract: To enable robots to search for the indoor odor sources by imitating the foraging behavior of ant colony,a multi- robot cooperation strategy is proposed based on a modified ant colony algorithm(ACA).The modified ACA includes three stages,which are local traversal search,global random/probability search and pheromone update.A verification procedure is introduced into the iteration process to localize multiple odor sources.Simulation results show that the local traversal search can enable the robots to move towards the odor source gradually,and to set an odor concentration threshold(OCT)in the global search stage can prevent the robots from cluttering together.Finally,the multiple odor source localization performance of the robots which start at different entrances is validated.