Abstract: In order to investigate the defects such as the cavity influences on the wedge splitting performance of the concrete, the cavity is made equal to a loss of the height of the longitudinal section and the calculation formulas for the wedge splitting fracture parameters of the concrete with cavity defects are derived. And then 8 groups including 32 specimens are designed for the wedge splitting tests using the improved testing instrument developed by our team. The influences of different sizes and locations of the cavity on the wedge splitting performance of the concrete are analyzed. The test and calculation results show that along with the increases of the cavity size (diameters from 0 to 120 mm), initial load, instability load, initial CMOD (crack mouth opening displacement) and instability CMOD are respectively reduced by 43.59%, 23.75%, 39.85% and 54.50%. The cavity defects have smaller effects upon the initial toughness of the concrete as their values are stable, but the cavity defects have greater effects on the instability toughness of the concrete, and the instability toughness decreases by 46.20% with a increase in the cavity size. The influences of the cavity location on the wedge splitting performance are relevant to a crack propagation path. When the crack passes through the cavity, the related fracture parameters are reduced; when the crack is far away from the cavity, it has a little effect.