Abstract: The effect of different strain rate on the microstructure and mechnical properties of 5083 Al-based alloy was studied.The results showed that the strength of the alloy decrease with the increase of the strain rate.The stress-strain curves exhibited serrated yielding behavior after a certain amount of plastic deformation.The stress serrations were upward at fast strain rate but downward at low strain rate.The analysis showed that stress increase caused by the decrease of strain rate is mainly due to the interaction between dislocation and solute atoms.The upward stress serrations was due to pinning process and the downward stress serrations was due to unpinning process.