We explore range expansion along an fixed direction with a wireless system consists of a fixed number of mobile robots which do cooperative transmission (CT). The emphasis is on optimal the clusters and locations of clusters to maximize the multi-hop range along a line based on the glowworm swarm optimization (GSO). We build the CT model which can't be solved by conventional method, and solve it by using GSO algorithm to get the optimal result. In GSO algorithm, every mobile node was considered as a glowworm, and the intensity of signs was the intensity of luciferin. Firstly, the initial deployment of nodes is set randomly. Then, after calculating the value of the movement probability, the direction of movement is determined as well as the direction of movement under the constraint of outage probability in CT model. Finally, the deployment of cluster nodes is finished by iterations. Simulation results show that our improve GSO (IGSO) algorithm has such characteristics as high precision and time saving by comparing with traditional GSO and ant colony system (ACS) algorithm.