The mechanism of nano silicon physiologically regulating the alleviation of aluminum toxicity in the root tip and root edge cells of pea under low pH including pH 3.5， pH 4.5， and pH 5.5 was analyzed by PEI–induced silica electrostatic adsorption to form nano-silica shells for biomimetic mineralization to study the effects of the mineralization of nano silicon on the protective mechanism of the root tip and root border cells of pea under different pH and aluminum environments. The results showed that the treatment of Aluminum at various levels of pH decreased the activity of root border cells， while the treatment of silicon significantly increased the activity of cell in response to aluminum toxicity. The content of aluminum and ROS in silicon treated cells were lower than that in silicon deficient cells， and the mitochondrial membrane potential of the cells increased after the addition of silicon. Aluminum toxicity inhibited the elongation of root tip in peas. The effect of adding silicon to alleviate the root tip inhibition under pH 3.5 with the treatment of aluminum was not significant， but the elongation of root tip was significantly increased under pH 4.5 and pH 5.5. As the pH of aluminum treatment increased， the content of aluminum in root tips decreased， and the content of aluminum in root tips after the treatment of adding silicon was higher than that after the treatment of silicon deficiency. Silicon enabled more negatively charged functional groups on the cell wall to participate in the resistance to aluminum stress， reducing the absorption peak of various components of the cell wall including pectin， cellulose， hemicellulose， proteins， etc. Nano silica shells were formed on the cell surface under pH 4.5 and pH 5.5 of aluminum environment， and silicon aluminum deposited on the cell wall to form aluminosilicates. It is indicated that the mineralization and deposition of nano silicon on cells under low pH can alleviate the toxic effects of aluminum ions.