Abstract: In order to study the high temperature hot deformation behavior of Q690 steel for construction machinery, the high temperature compression test of Q690 steel for construction machinery was carried out by using Gleeble3800 thermal simulation testing machine. The true stress-true strain curve of Q690 steel was analyzed. The hot deformation equation and hot processing map of Q690 steel were established. The results show that the flow stress of the Q690 steel decreased with the increase of deformation temperature and the decrease of deformation rate. The hot deformation activation energy of Q690 steel was 432.354 5 kJ/mol.The hot processing map showed that the Q690 steel had instability zone in the whole temperature range, and the instability zone should be avoided in the actual production process. When the temperature was 1 080-1 150℃ and the strain rate was 0.01-0.3 s^-1, the power dissipation factor of the Q690 steel was higher than 0.3, which was the best hot working area of the Q690 steel.