Abstract: The tensile properties of 5083 /6063 dissimilar aluminum alloy joint was investigated at low temperature by means of tensile properties test. The fracture morphology was examined and analyzed by Scanning Electron Microscope( SEM). The results showed that the ultimate tensile strength and elongation increased with reduction of test temperature from 293 K to 77 K.The ultimate tensile strength of samples was 129 MPa,175 MPa and 220. 5 MPa at 298 K,113 K and 77 K,respectively. By observing and analyzing the tensile facture,the 5083 /6063 dissimilar aluminum alloy exhibited ductile facture with dimple at low temperature.