Abstract: In this paper,a primary study on fatigue performance of strengthening RC beams by using prestressed aramid fiber reinforced polymer(AFRP)sheets with permanent anchor was carried out.Based upon the experimental study of four specimens,the beams strengthened with prestressed AFRP sheets were compared with the beams strengthened with non-prestressed AFRP sheets on the fatigue failure,fatigue life, mid-span deflection and strain.And the effects of different prestress levels of AFRP sheets on these behaviors were discussed.The experimental results demonstrated that,for the comparison between the beams strengthened with prestressed AFRP sheets and the beams strengthened with non-prestressed AFRP sheets, the fatigue life was increased by 33 % to 74 %.The fatigue failure of the RC beams strengthened with AFRP sheets arose from the fatigue fracture of steel bars.This was because that fatigue performance of the AFRP sheets was better than that of the steel bars.Finally,the formulas for computing the fatigue life of the beams strengthened with prestressed AFRP sheets were proposed.