Abstract: Nine RC short columns retrofitted with Prestressed Steel Jacket (PSJ) were tested under statical loadings to investigate the shear resistant behavior and shear bearing capacity of retrofitted columns. The main test parameters are prestressing level of PSJ () and configuration parameter of PSJ (). The test result indicated that shear strength of retrofitted column is enhanced effectively and the ductility of the columns is improved significantly. The shear resistant mechanism of PSJ is discussed and the shear bearing capacity of retrofitted columns are analyzed. It is indicated that the shear coefficient of PSJ depends on the prestressing level and configuration parameters. According to the superposition method, a formula is suggested to calculate the shear bearing capacity of retrofitted columns, and the calculated results show good agreement with the test results.