The ROS metabolize and root growth of Vigna unguiculata L.cultivar ‘T6’(Al-tolerant) and ‘S3’(Al-sensitive) root tip was measured to analyze the relative between Al tolerance and ROS metabolize.The results show that:(1)The root length of ‘T6’ and ‘S3’ was inhibited with the increase of Al,the decrease of ‘S3’ was larger than that of ‘T6’.(2)The superoxide anion radical (O^-·₂),H₂O₂ content,MDA content and plasma-membrane permeability of ‘T6’ and ‘S3’ root tip increase significantly by Al increase from 0 to 500 μmol·L^-1,but ‘S3’ made more increase than that of ‘T6’.(3)The SOD,POD,CAT,APX,GR,AsA,GSH of ‘T6’ and ‘S3’ root tip increased after exposure to 0 to 500 μmol·L^-1 Al.The increase range of SOD of ‘S3’ root tip was higher than that of ‘T6’,but increase range of POD,CAT,APX of ‘S3’ root tip were lower than that of ‘T6’.We presume that ‘S3’ root tip accumulated more ROS and increased the oxidative stress,then result in the inhibition of root growth.