The hot compression deformation behavior of AZ61B magnesium alloy has been investigated by using a Gleeble-1500D thermal simulator. The samples were compressed to a reduction of 50% at two temperatures (623 and 673K) with different strain rates (0.01, 0.1 and 1s-1). The relationships between flow stress and deformation temperature were analyzed, and the deformation activation energy and stress exponent were calculated based on the experimental results. With aid of the optical microscopy, scanning electron microscopy (SEM) and electron back scattered diffraction (EBSD) techniques, the microstructure and micro-texture of the deformed samples were characterized. The effects of the temperature and strain rates on the hot compression behavior of the AZ61B magnesium alloy have been investigated by detail analyses of the flow stress and microstructural characteristics of the deformed samples. For the 50% compressed samples, dynamic recrystallization occurred during the hot compression. The orientations of the dynamic recrystallized grains with equiaxed shape were investigated by EBSD technique. The relationships among the flow stress, dynamic recovery and recrystallization have been discussed by considering both the temperature and strain rate effects.