Different mass fractions (0, 3, 6, 9, 12, and 15%) of ethyl acetate were added to bio-oil for improving its storage stability during storage at 40°C for 35 days. For different bio-oils during storage, physical properties were characterized and chemical components were determined by GC–MS and FT-IR. The results of properties characterization showed that, addition of ethyl acetate could instantly lower bio-oil viscosity, water content, and dramatically decrease the rate of aging. pH value of bio-oil can be instantly improved by adding ethyl acetate. GC–MS results revealed that addition of various content of ethyl acetate into bio-oil and its storage at 40°C for 35 days could both lead to disappearance of previous compounds and generation of new compounds. FT-IR results showed that addition of various content of ethyl acetate into bio-oils and its storage at 40°C for 35 days could slightly change the wavenumbers of substantial functional groups in bio-oils.