In this paper, the pool boiling heat transfer performances of copper fiber porous materials which were composited with four different fiber diameters (i.e 30μm, 50μm, 100μm and 160μm) and copper plane plate were investigated under the atmospheric pressure. The experiment results show that the heat transfer performances of the copper fiber porous materials with the porosity of 90%, 80% and 75% are much better than that of the Cu plane plate when the superheat is below 20oC. The heat transfer performance of the copper fiber porous materials is enhanced as decreasing the fiber diameter when the porosity of copper fiber felt was 90%. When the fiber diameter is 160μm, the heat transfer performance is enhanced as decreasing porosity of copper fiber felt. There are many factors which can affect the pool boiling heat transfer, such as the number of active evaporation core, the resistance of bubble overflow and the fiber capillary attraction, and so on. Then, there should be different optimal pore structures under different working conditions.