Abstarct: Design problems, deficiency in construction quality, use of low quality materials and change in the application of structures are the main reasons that make the existing structures can not satisfy the criteria of design codes and therefore, need to be repaired and retrofitted. Retrofitting is performed in different elements of a structure such as beams, columns, slabs, etc. Among these elements, columns are very important in transferring the load and the stability of structures. Therefore, appropriate method should be selected in retrofitting of these elements. Over the past decades, use of FRP as a kind of advanced composite materials has come to the forefront of retrofitting techniques. These materials possess many attractive engineering qualities such as high ratio of strength to weight, high strength to fatigue and high resistance to corrosion, that are leading to their increased application. There are many theoretical models to determine the increase in strength and ductility of concrete confined with FRP. Comparison with available experimental data indicates a large degree of uncertainty in these models. The development and improvement of design codes affect the optimum use of FRP. For this reason it was decided to investigate the index reliability design code for Iran and United States with reliability theory. One of the effective factors on index safety study is to identify thoroughly all available probability factors. Unfortunately, there is not any comprehensive study on load and resistance variables in Iran. In addition, studies on the reliability of reinforced concrete columns strengthened with FRP, are very limited. For this reason it was decided to make a statistical population on strength of columns and investigate the index reliability for design code with Rackwitz-Fissler method.