At present, magnesium alloy is the lightest metal that can be used as structural material. The present research on rolling for magnesium alloys will bring a great significance in promoting their application. This paper emphasizes on the effects of one-pass heavy reduction, total pass number and rolling temperature on microstructure and mechanical properties of AZ31 magnesium alloy. Some related rules have been summed up. It has been found that there was no obvious difference on microstructure and mechanical properties between hot rolled samples with different one-pass heavy reduction rates. With the same total reduction, strength rised as total pass number increased in multi-pass rolling. However, mechanical properties of sample had a close relationship with the reduction rate of last pass. The microstructure obtained at 300 degrees C rolling was finer than that obtained at 400 degrees C rolling. Samples rolled at lower temperature exhibited higher strength.