Abstract: To analyze size effect of concrete columns under large eccentric loading,two groups reinforced concrete columns were produced,the eccentricity were 0.6h₀ and 0.9h₀ respectively,and the specimen were 200 mm × 200 mm,400 mm × 400 mm,800 mm × 800 mm respectively. The authers studied damage characteristics,ultimate capacity,sectional strain properties,deformability and curvature of reinforced concrete columns with different size under the same eccentricity. The results show that the size has less effect on damage characteristics and the sectional strain properties of columns,and the size effect on ultimate capacity and deformability is obvious. The storage for capacity safety and the deformability of columns are decrease with the dimensions increasing.