Purpose To evaluate choroid thickness and macular retinal metrics in treatment naive retinal vein occlusion (RVO) patients with serous retinal detachment (SRD) before and after intravitreal anti-vascular endothelial cell growth factor (VEGF) injection and to elucidate the possible role of choroid in the development of SRD and the potential role of SRD as a prognostic parameter. Methods This is a retrospective study involving 85 RVO patients, 41 central retinal vein occlusion (CRVO), and 44 branch retinal vein occlusion (BRVO), with macular edema: 21 central retinal vein occlusion and 22 branch retinal vein occlusion with SRD and the rest without SRD. Patients were evaluated with ophthalmic examinations and swept-source optical coherence tomography (SS-OCT) both before and 4-6 weeks after intravitreal anti-VEGF treatment. Choroid thickness and retinal metrics were measured and compared between SRD and non-SRD groups within each RVO subtype. Results In both CRVO and BRVO patients, the mean central subfield foveal thickness (CSFT) and central subfoveal choroid thickness (CSCT) of the SRD groups were thicker than those in the non-SRD groups (p < 0.05) at onset. After one anti-VEGF injection, CSFT and FNRT decreased in all groups (p < 0.05). The CSCTs were thicker in the SRD groups compared with the non-SRD groups (p < 0.05). The mean changes of CSFT were more remarkable in the SRD groups (p < 0.05). Conclusion Thicker choroid was a feature of naive RVO patients with SRD and SRD may be an indicator of better anatomical recovery of retina in RVO patients after a single dose of anti-VEGF treatment.