Strengthening by CFRP sticking to steel plates can exploit advantages of the two materials. The viscoelastic nature of FRP composites make it imperative that the creep behavior of the composite material should be taken into account for the analysis and design of any strengthening structure. In this paper, a creep experiment of a CFRP-steel composite under different stress levels has been introduced. The failure types, average yield load, ultimate loads, and initial longitudinal elastic modulus of the composite specimens were investigated through the short-term tests. Material coupons were subject to axial tensile load at various stress levels for time duration up to 500 hours in the long-term tests, and the results indicate that the strain increase with time and the ultimate creep strain increase with the increase of the initial strain. For the evaluation of the viscoelastic behavior of the composite material, the model developed by Findley was adopted. The agreement of the model results with the experimental data indicates this medel could be used to estimate the creep effectively at engineering analyses.