Abstract: As a high-quality lightweight metal material, rare earth magnesium alloy has a good application prospect in the aerospace field. The spark plasma diffusion bonding（SPDB） process was used to join VW94 rare earth magnesium alloy without interlayer and with Cu, Ag and Ni interlayer. The diffusion bonding experiment was carried out under the process parameters of 480 ℃ -2 MPa-120 min. The microstructure and mechanical properties of the diffusion joint were analyzed.The results show that VW94 rare earth magnesium alloy can achieve high quality diffusion bonding without adding metal interlayer, and the interfacial shear strength is 109 MPa. The Cu and Ag interlayers can form good diffusion joints with rare earth magnesium alloy, respectively. Cu atoms mainly diffuse into the LPSO phase to form Mg₁₂（Gd, Y）₁（Cu, Zn）₁ phase, and Ag atoms diffuse into the α-Mg matrix to form Mg-based solid solution Mg（ss, Ag）. Zn and Zr atoms will gather near the joint surface. The shear strength of the joint interface is 106 MPa and 109 MPa, respectively, reaching 82.8% and 85.2% of the shear strength of the base material. At this temperature, Ni atoms basically do not diffuse, and the shear strength of the bonding interface is only 16 MPa, which was only 12.5% of the shear strength of the base metal.