The flatwise tension, flatwise compression, edgewise compression, flexure and shear properties of polymethacrylimide (PMI) foam/ carbon鄄fiber epoxy resin composites sandwich structures have been tested. And the failure modes of mechanical testing specimens have also been analysed. Results showed that the flatwise tension, flatwise compression and shear properties mainly depended on the properties of PMI foam core. The flexure testing specimens could better reflect the shear properties of foam. In addition, the foam sandwich structures had excellent edgewise compression and flexure properties. The edgewise compression strength and modulus of carbon鄄fiber epoxy panel (1. 05 mm) / foam (30 mm) sandwich structure are respectively 26. 5 MPa and 5. 88 GPa. The flexure stiffness and modulus of foam sandwich structure are respectively 3. 05 kN·m2 and 97. 5 GPa.