Abstract: According to functional differences of different parts of a heat pipe, a novel multi-scale composite structure porous wick heat pipe was designed and fabricated with nano-porous copper powder and irregular copper powder as raw materials. The porous wick at evaporation section of the heat pipe consisted of a two-layer structure, namely a small-pore layer sintered with nano-porous copper powder on the pipe wall side and a large-pore layer sintered with irregular copper powder on the working medium chamber side. The porous wick at adiabatic section and condensation section had one large-pore layer sintered with irregular copper powder. The heat transfer performance of the heat pipe was investigated by using a self-assembled heat transfer performance test device. The results show that the small-pore layer of the multi-scale composite structure porous wick could provide higher capillary forces, and the large-pore layer could provide larger working medium flow channels, thereby improving the heat transfer capacity of the heat pipe. Comparing with the monolayer uniform porous wick heat pipe, the multi-scale composite structure porous wick heat pipe exhibited a higher heat transfer ability under anti-gravity conditions; and the heat transfer limit power was as high as 90 W under the completely anti-gravity condition (tilt angle of 90°), which was 2.9 times and 2.3 times higher than that of monolayer uniform porous wick heat pipes prepared with nano-porous copper powder and irregular copper powder, respectively.