The behaviour of Concrete Filled Steel Tube (CFST) beam strengthened with Carbon Fibre Reinforced Polymer (CFRP) sheet was investigated numerically in this paper. Nonlinear analysis using ABAQUS Finite Element (FE) software to assess the behaviour of square and circular CFST beams wrapped from bottom side with U shaped of CFRP sheet using different length and multi layers. The FE models were verified accurately through successful comparison with existing experimental study done by others. The results obtained from the study show that various lengths and multiple layers of CFRP sheets directly affect the ultimate moment capacity of CFST beams, where the ultimate moment capacity of the CFST beams was improved by increasing the layers of CFRP sheets specifically for beams wrapped along 75% or more of their length. Meanwhile, CFRP delamination failure has been observed for beams wrapped along 50% of their length, where delamination failure occurred earlier with an increasing number of CFRP layers. Moreover, by increasing the wrapping length of CFRP sheet to more than 75% of the beams length did not lead to further improvement in the beams moment capacity for each specific number of CFRP layers.