||Flavonoid is one of the polyphenolic molecule from living nature such as fruit and plant. Catechin is a component from green tea that is generally known for biochemical properties such as anti-inflammation, anti-oxidant, and anti-cancer. Many flavonoids including catechin are poorly soluble in water which is a serious drawback to be used in bio-applications. In this study, we increased aqueous solubility of catechin through complexation with poly(ethylene glycol) (PEG). The experimental procedure does not consist a complicated conjugational process. The preparation is simple but the solubility enhancement is high (at least 50 mg/ml). In this study, highly soluble nanocomlex of catechin is used in in-vivo to treat dry eye diseases. The nanocomplex showed anti-inflammation property and increased goblet cell density which helps dry eye diseases. The optimal weight ratio of complex was PEG-catechin 10 for dry eye model.