Abstract: An active olfaction implementation scheme based on evolutionary gradient search(EGS)using a swarm of robots is put forward.Firstly,a time-variant airflow environment using Fluent software is set up.Secondly,the EGS-based robot active olfaction implementation procedure in the simulated environment is presented,including plume finding,plume tracking and odor source declaration.To overcome the drawback of the EGS algorithm,i.e.its performance will degrade when the number of robots is not big enough,the information of wind direction is also used.Simulation results validate the proposed search scheme.Comparing with the traditional concentration-gradient based search methods using single robot,advantages of the EGS-based method are demonstrated.