To investigate the dynamic performance and unloading failure characteristics of coal under non-hydrostatic conditions, based on 3D dynamic and static loading experiment, the effect of unloading method on the macroscopic failure characteristics of unloading coal samples after dynamic disturbance was studied. Firstly, Ф50 mm split Hopkinson pressure bar system was used to carry out the dynamic experiment of coal sample under 3D dynamic and static loading for the purpose of studying the influence of axial compression and strain rate on the dynamic response of coal samples. Secondly, based on the response surface theory, a regression model considering the interaction of factors was constructed by using the central composite test method and the significance of single factor and factor interaction were analyzed. Afterwards, combined with factor interaction, Weibull distribution and Drucker-Prager criterion, the strength statistical damage constitutive model of coal was modified. The reliability of the model was verified by comparing the theoretical and experimental results. Finally, with the help of loading and unloading electro-hydraulic servo device, the influence and mechanism of axial pressure, impact pressure and unloading mode on the failure characteristics of coal samples were explored. The results showed that the constructed strength statistical damage model has a correlation coefficient R²≥0.88, which can characterize the dynamic response behavior of coal samples. The coal samples with synchronous unloading after impact are mostly spalled, and the tensile interface moves backward and eventually disappears with the increase of axial pressure, unable to form spall failure. The failure modes of coal samples under non-synchronous unloading mainly include overall integrity, spalling and compression-shear failure. However, when the impact pressure is in the range of 0.4 to 0.6 MPa and the axial pressure is 14.5 MPa, a mixed failure mode of ‘spalling + compression-shear’ is observed.