A stable liquid formulation includes a fusion protein having an Fc domain of a human immunoglobulin G (IgG), in particular, a protein in which an Fc domain of a human immunoglobulin G (IgG) and a soluble extracellular domain of a vascular endothelial growth factor (VEGF) receptor are fused (e.g., aflibercept)). A composition for stabilizing a protein and a method for stabilizing a protein in which an Fc domain of an IgG and a soluble extracellular domain of a VEGF receptor are fused are disclosed. The present invention improves therapeutic effects on various ophthalmic diseases (e.g., retinal vein occlusion, diabetic macular edema, choroidal neovascularization and wet age-related macular degeneration, etc.) caused by abnormal angiogenesis, while pursuing stabilization of bioactivity through a stable liquid formulation suitable for intravitreal injection of an anti-VEGF-Fc fusion protein including aflibercept.