In this paper, as the example of AZ31 magnesium alloy, the process of magnesium alloy spun tube with the sixth spinning passes has been studied, and the microstructue evolution and the micro/nan mechanical properties of the tube billet has been analyzed. The magnesium alloy tube with the wall thickness of 1 mm from the wall thickness of 10 mm has a good forming and no bulge defects, such as bump by power spinning testing. The microstructure of the tube samples with several spinning passes was analysed by optical microsco. The results show that the grain distribution from original coarse and uneven grain transform to main twin, even and fine grain characteristic. The nanoindentor properties were tested by G200 Micro-nano mechanics test system. The results present that the hardness increased with the spinning passes, and the hardness were 0.377 GPaand 1.053 GPa, respectively. The modulus of original and after power spinning magnesium alloy tube samples were with features of plastic fracture. However, The fracture original magnesium alloy tube was dimple fracture with larger and deeper. On the contrary, the fracture after power spinning was dimple fracture with small and shallow.