Attention selectively prioritizes goal-related information to facilitate visual perception. Various studies have demonstrated that visual attention enhanced the efficacy of neuronal pairs’ interactions between the hierarchically structured visual cortex. The primary visual cortex (V1) also exhibits a hierarchical connection between simple (S) and complex (C) cells. We wonder about the impact of visual attention on neuronal interactions within V1, encompassing both the extent and manner in which it occurs. When monkeys engaged in an attention-involved task, we simultaneously recorded neuronal pairs' activities from them. Subsequently, we utilized Granger causality analysis to quantify neuronal interactions and investigate the influence of attention on that. We found attention enhanced the inhibitory interaction between paired neurons, which only significantly occurred between simple and complex cells. Further, the S-to-C feedforward interactions displayed the largest enhancement with visual attention. By manipulating the attentional focus placement, we discovered that attention would not trigger distinct neuronal interaction, but instead enhanced the directed communication within S-C hierarchy. Together, these findings contribute to the existing hierarchical structure model between simple and complex cells and provide further insights into the impact of spatial attention on neuronal interactions within V1.Study Schematic