Abstract: In order to investigate the safe service range of W-Cu functionally graded material (FGM) in the cyclic thermal shock process, layered W-10wt%Cu/W-20wt%Cu/W-30wt%Cu gradient materials were prepared by laminated pressing and atmospheric sintering using electroless W-10wt%Cu composite powder and Cu powder as raw materials. Thermal shock experiments were carried out under temperature differences of 600℃, 800℃ and 1000℃. The microstructure and thermal properties of the sintered gradient samples were investigated under different thermal shock temperatures and times. The experimental results show that with the increase of thermal shock temperature, Cu gradually exudes to the surface of each gradient layer. When the thermal shock temperature reaches 1000℃, a large number of Cu appear in clumped sheets on the surface of each gradient layer. Simultaneously, interface cracks are found at the interface of W-20wt%Cu/W-30wt%Cu. With the increase of the number of thermal shock times, in the W-10wt%Cu layer, the Cu exudation surface leaves micro pores in the interior. In addition, the thermal conductivity of W-Cu FGM decreases with the increase of thermal shock times. After thermal shock at 1000℃ for 200 times, the thermal conductivity of room temperature drops from 200.54 W·(m·k)⁻¹ to 159.23 W·(m·k)⁻¹, decreasing by 20.60%. This result reveals the coupling failure mechanism of crack formation and microstructure changes in thermal shock cycles, and clarifies the scope of safe service of W-Cu FGM.