FRP bars were used to improve the mechanical properties of bamboo beams for civil engineering without changing the existing bamboo processing technology in this paper. Three bamboo beams, including one control beam and two FRP-reinforced beams were tested. The effects of various types of FRP bars were compared, including CFRP and BFRP. The results show that the ultimate displacements of reinforced specimens are less than the control specimen. The FRP bars can enhance effectively the cross-section stiffness of bamboo beams. CFRP bars can reduce about 30% strain and BFRP bars can also reduce about 10% strain for the tensile bamboo fiber. The FRP bars in the tension zone can share tensile stress of bamboo fiber. The cross-section stiffness still controls the structure design for the FRP bars reinforced bamboo beams.