This paper presents 3D and 2D finite element models to analyze strengthened reinforced concrete (RC) Beam-Column Connections with carbon fiber reinforced polymer (CFRP) which has become familiar technique in the last decade. According to the demand of seismic concept design of buildings, frame structures should have multiple lines of seismic resistance, one of which is the strong column-weak beam. But for RC frame, column plastic mechanism not the beam plastic mechanism was normally found. So the problem about strengthening of strong beam-weak column connections by increasing the capacity of those zones by FRP, with the objective of relocating the potential plastic hinges from the columns to the beams needs to be investigated in depth. Experimental results in the literature showed that interfacial debonding of FRP may be occurred. The current study takes the debonding failure mode into account by considering cohesive surface inserted in the adhesive layer. The proposed cohesive surfaces take the slippage into account considering the cohesive surface fracture energy. The numerical models are verified utilizing five beam-column connections available in the literature. The numerical results of 3D and 2D models for the RC beam-column connections strengthened with FRP agreed well with the experimental results. Additionally, the effect of the cohesive surface parameters, the CFRP plate length, the axial load level and the retrofit scheme on the behavior of CFRP-strengthened RC Beam-Column Connections are investigated