Abstract: In order to study the mechanical properties of Glass Fiber Reinforced Polymer (GFRP) ultra-long two-way stress insulation connectors (UT connectors) suitable for prefabricated sandwich walls with ultra-thick insulation layer, push-out tests of six GFRP UT connectors shear specimens and axial compression tests of four compression specimens were carried out. The results show that the shear specimens of GFRP UT connector finally have concrete damage in the anchorage zone, while GFRP UT connectors have no obvious damage. The bearing capacity of C40 group is 1.04 times that of C35 group, and the ductility is increased by 13.16%, but the stiffness change is not significant. Compared with the shear specimens without insulation board, the bearing capacity of the EPS insulation board group is increased by 29.64%, the ductility is increased by 7.89%, and the stiffness is increased by 17.22%, and the EPS insulation layer can delay the damage development of the shear specimens. The final failure mode of GFRP UT connector under compression is concrete punching shear failure. Compared with the C35 group, the bearing capacity of the C40 group is increased by 10.33%, the stiffness is increased by 3.78%, and the ability to resist damage is stronger, but the ductility of the specimen is reduced. The failure modes and stress mechanisms of shear and compression specimens were analyzed by combining tests and finite element models. Based on the maximum principal tensile stress criterion, the calculation method for the shear bearing capacity of GFRP UT connectors was established. By determining the punching failure surface of concrete under axial compression, the calculation method of axial compression capacity of GFRP UT connectors was proposed. The calculated values are in good agreement with the test results.