Abstract: Fatigue tests were conducted on one bare and five carbon fiber reinforced polymer (CFRP)-repaired steel compact-tension specimens (CT specimens) to compare the fatigue behavior effects of bonded CFRP plates or carbon fiber sheets. CFRP type, patch configuration and material quantity were designated as three variables in the experiment. Beach marking technique and digital image correlation (DIC) technology were employed to measure and record fatigue crack propagation as well as strain distribution of the specimens’ surfaces. The techniques helped to explain the resistance contribution from CFRP patches under fatigue loading. The fatigue test results were analyzed in terms of fatigue life and fatigue crack growth rates (FCGR) to offer practical instructions on adhesively-bonded CFRP repair strategy. Results show that CFRP patches reduce and even forestall the growth of FCGR to prolong the fatigue life. In one case the fatigue life of a CFRP-repaired specimen increases to 314% compared to theunrepaired specimen. Double-side strengthening outperforms the single-side counterpart. The increase of carbon fiber sheet layers extends the fatigue life within a limit. CFRP plates show a disadvantage compared with carbon fiber sheets with a similar stiffness due to their pasting defect sensitivity. CFRP debonding and delamination predominate the failure modes in carbon fiber sheet-repaired specimens while adhesive layer failure and CFRP debonding reign in the CFRP plate-repaired ones. It can be inferred that interfaces are the weaknesses in fatigue failure and deserve further improvement.