Activation of microglia and inflammation‐mediated vascular damages are suggested to play a decisive role in the pathogenesis of various retinopathies. The inducible nitric oxide synthase (iNOS) was required for activated microglia‐mediated injuries. However, the induction mechanism of microglia activation during retinal vascular diseases is still elusive. Here we showed that IL‐17 induced microglia activation with high expression of iNOS and promoted the development of retinal vascular diseases. IL‐17‐dependent activation of the STAT3‐iNOS pathway was essentially required for microglia activation, which promoted endothelial cell growth and accelerated vascular leakage and leukostasis via IL‐6 in vitro and in vivo. Taken together, our data provide novel mechanistic insights on microglia activation‐mediated retinopathy, unveil the specific role of IL‐17 on microglia, and define novel therapeutic targets for treating retinal vascular diseases.