In this paper, properties of glass fiber-reinforced thermoplastic polymers (GFRTP) were evaluated using recycled polyester (rPET) for injection molding bicycle frame. The effect on thermal and mechanical properties of rPET reinforced glass chop fiber according to fiber cross section and fiber content ratio were studied. The crystallization temperature of glass fiber (GF)/rPET, a glass fiber added thermoplastic composite, was higher than the crystallization temperature of rPET pellet without a glass fiber, and the shape of the exothermic curve was sharper. Mechanical characteristics of a GF/rPET thermoplastic composites has been increased by increasing fiber contents, than above a certain level did not longer increased. And mechanical properties of flat glass fiber reinforced rPET with low void volume were most excellent. In order to prove the validity of the experimental results, finite element analysis of thermoplastic composite was performed by Digimat and Abaqus to compare the experimental values according to the cross sectional shape and volume fraction of glass fiber. The results of finite element analysis showed a similar tendency between the experimental results and the analysis results.