Different forms of Aluminum(Al) have different harm intensities to different plants,so the study of vegetal responses of plants to different forms of Al stress is of great significance.In this research,Fagopyrum esculentum (buckwheat) and Fagopyrum cymosum(gold buckwheat) were cultured in soil to studied the various forms of Al in the their rhizosphere soil and the effect of the forms on plant growth,under four different Al treatment concentrations(0,0.1,0.2,0.4 g Al3 /kg).The result revealed that when acid-aluminum concentration was less than 0.2 g/kg,buckwheat and gold buckwheat had higher shoot length,shoot weight and water utilization efficiency(WUE),indicating they adapted this condition at a certain extent.When acid-aluminum treatment reached 0.4 g/kg,it was found that the photosynthesis of buckwheat and gold buckwheat were greatly inhibited,the obvious aluminum toxic symptom as plant rhizosphere soil pH values decreased to the least,while the amount of different aluminum forms extracted from plant rhizosphere soil solutions increased to the most.Combining with those conclusions,it can be inferred that the threshold of actived Al toxicity in the rhizosphere soil on buckwheat was between 0.106~0.143 mg/g,while that on gold buckwheat was between 0.046 ~ 0.057 mg/g.