In view of the requirements of high tensile strength and shear strength mechanical properties of materials and connection methods for spacecraft products under harsh working conditions， experiments designed aim to verify the tensile and shear properties of vacuum brazing and flame brazing specimens in profound hypothermia to high temperature environments. Vacuum brazing samples show significantly better results than those of flame brazing. The tensile strength of vacuum brazing specimens can reach 536 MPa at -233 ℃ and the shear strength 260 MPa. The shear strength of vacuum brazing specimens is 300 MPa at -150 ℃， and shear strength in the normal temperature is 212 MPa. Furthermore， the effect of vacuum brazing process on the properties of alloy steel 40CrNiMoA has been studied. The vacuum brazing process reduces the tensile strength by about 38% and the surface hardness by about 25%. As the results indicated， the tensile strength and shear strength of the vacuum brazing samples at 200 ℃ are 804 MPa and 239 MPa， respectively. The effects of different welding processes on the mechanical properties of the structure after welding are studied through the experiments. The test results play an instructive role for the follow-up spacecraft structure designs.