Effects of calcium and silicon on detoxification of aluminum (Al) of buckwheat were studied with solution culture experiments. The results showed that either calcium or silicon could alleviate toxicity of Al. The root activity, the content of soluble protein and the activity of peroxidase (POD) of buckwheat leaves were increased, and malondialdehyde content (MDA, showing lipid peroxidatic reaction) of buckwheat leaves was decreased, when addition of calcium or silicon under the stress of Al. The inhibition effect of Al toxicity on soluble protein was completely offset by either calcium or silicon in first bloom stage. However, the alleviating effects of calcium or silicon on aluminum toxicity were limited when the concentration of Al increased. The alleviating effect of calcium was better than that of silicon.