With hydroponic culture,the single toxic effects of Cd2+,Hg2+ on the peanut seed germination,seedlings main physiologicalbiochemical characteristics were studied.The result showed that:The frequency of seed germination decreased when the Hg2+ concentration reached 5 mg/L or Cd2+ concentration reached 20 mg/L;When the Hg2+ concentration reached 25 mg/L or Cd2+ concentration reached 10 mg/L,the growth of seedlings was inhibited and the root decayed;The Hg2+ concentration was significant negative correlation with the chlorophyll a,but significant positive correlation with chlorophyll b and significant positive correlation with the activity of CAT.The activity of CAT and concentration of chlorophyll were all significant negative correlation with Cd2+ concentration.