Recently, rhythmic visual stimulation (RVS) has been demonstrated to affect the brain function by entraining neural oscillations. However, less is known about how RVS influences the functional connectivity across the whole brain. Here, we applied a graph theoretical approach to analyze the electroencephalography (EEG) connections of 60 nodes when subjects deployed their attention on visual task with different background stimulation, i.e. no background flicker, jittered flicker, and RVS of 6, 10, 15 and 40 Hz, respectively. Thirty-three subjects participated in this study. As a result, the 40-Hz rhythm led to the significantly fastest reaction among all conditions. Furthermore, significantly higher clustering coefficient (C) and small worldness (σ) of θ-band brain network were observed for higher-frequency RVS, which were significantly negatively correlated with reaction time (RT) (C-RT: r =-0.917, p =0.010; σ-RT: r =-0.894, p =0.016). In addition, we found an increase in the connections between dorsolateral prefrontal and visual cortices under RVS compared to no flicker. Our results indicate that RVS can improve the efficiency of brain cortical functional network to facilitate attention.