Abstract: In order to solve the problem of continuous collapse caused by the instability of the key compression struts in fiber reinforced polymer (FRP) space truss structure, a casing buckling restrained brace for the overall instability of glass fiber reinforced polymer (GFRP) tubes composed of stainless steel casing and bolt connection system was proposed. In order to analyze the influence of the casing buckling restrained brace on the axial compression performance of pultruded GFRP tubes, axial compression tests were carried out on three GFRP tube specimens and four GFRP tube specimens with casing buckling-restrained brace. The loading course and failure form of specimens were observed, and the load-displacement curves and load-strain curves were obtained, and the ultimate bearing capacity and failure mode were compared. At the same time, the finite element model was used to analyze the influence of different slenderness ratios of GFRP tubes, core and casing gaps and casing thicknesses on the axial compression performance of GFRP tubes. The results show that: the casing buckling restrained brace can effectively restrain the overall instability deformation of GFRP tubes, its ultimate bearing capacity and ductility are improved, and the GFRP tubes develop from instability failure to material strength failure; the larger the slenderness ratio of the core, the higher the ultimate bearing capacity of the GFRP tubes due to buckling of the casing compared with the critical load of the core instability, and the better the restraint effect; the greater the gap between the inner core and the casing, the better the ductility of the GFRP tube, but its ultimate bearing capacity will be reduced; too thin casing thickness will reduce the ultimate bearing capacity of GFRP tubes, but too thick will have no obvious restraint effect.