This paper makes an experimental and analytical investigation of cracks characteristics in Fiber Reinforced Polymer strengthened RC beams under different levels of sustained load and Reinforced ratio. As the equations available for conventional RC beams are inappropriate for the calculation of the short-term crack width in FRP-strengthened RC beams[8], a statistical analysis is carried out on available test data from international sources [6-9-10] and from the test results obtained in the current study (Concrete Labor- Civil engineering Department- Damascus University-2014) to establish a new equation that considers the effect of the FRP laminates. This equation is a correlation of stress in steel bars, concrete surface tension , and effective side cover. The long-term crack width is then related to the instantaneous crack width by empirical equations which are derived from the test results obtained in the current study.