The small punch test (SPT) has been widely used to evaluate the mechanical properties of materials for the nuclear industry due to its advantage of requiring minimal sample volumes. In this paper, the correlation between SPT and uniaxial tensile testing (UTT) is investigated for three materials used in the plasma-facing components of fusion reactors, namely Cu, CuCrZr alloy and W, whose mechanical properties vary significantly. From the views of mechanical properties and fracture morphologies, materials demonstrate consistent behaviours between SPT and UTT, which proves that the SPT is an effective method to characterize the mechanical properties and fracture mechanism of Cu, CuCrZr alloy and W. Moreover, the finite element simulation results of SPT for five other copper alloys with different mechanical properties are added, and the quantitative correlation equations of mechanical properties between SPT and UTT are established. One unified correlation equation between SPT and UTT can be established for the ductile materials with largely different mechanical properties. However, the introduction of a brittle material in the form of W invalidated the correlation equation. This work provides a reference for the study of mechanical properties of materials used in plasma-facing components by SPT.