Elements diffusion across the interface will result in poor performance during service, so it’s important to put a barrier layer between thermoelectric materials and electrode, and get them bonded perfectly as well. In this work, with copper as electrode and nickel foil as barrier layer, Cu/Ni/Mg2Si thermoelectric joint was prepared by the field-activated pressure-assisted synthesis (FAPAS) method, in which the in situ synthesis of Mg2Si and bonding between different layers were accomplished in one step. SEM, EDS and XRD were used to observe the microstructure, determine phase component and forming process of new phases, and obtain element distribution across the interface; thermal shock test and four probe method were used to evaluate the mechanical properties and electrical resistivity of the joint. The results show that the synthesized Mg2Si has high purity and stable coefficient of thermal expansion (CTE) at high temperatures. The nickel layer blocks the mutual element diffusion effectively in interface and gets bonded well with copper and the synthesized Mg2Si, respectively, accompanied by the formation of new phase, Mg2SiNi3 and Mg2Ni, in turn in the former interface. Based on good match of CTE in Cu/Ni/Mg2Si interfaces, the joint stays intact even experiencing 60 thermal shock cycles. With the increase of aging time, the thickness of interfacial diffusion layer gets wider, and the contact resistance increases subsequently, which roughly fits the linear relation with . The minimum contact resistivity of the joint is 112 μΩ?cm2 when the bonding temperature is 700℃.