Abstract: Compression fatigue experiments of WC-12Co cemented carbide were carried out on Gleeble 1500 under different thermomechanical conditions.The Vickers hardness of the alloy was tested,the microstructures were observed by SEM and TEM,and the deform mechanism was discussed.It is shown that with increasing experimental temperature and load,the continuity of WC skelectons is broken down,leading to the decreasing in hardness of WC-12Co alloy.The deform mechanism of WC-12Co alloy is that the alloy's plastic ability is offered by the slipping of dislocations in WC phase and the binder's martensitic transformation at low deformation temperature and stress.With the deformation temperature and stress increasing,the further deformation ability is offered by the movement of stacking faults in WC and the slipping of WC/WC interfaces.