Abstract: Adding Si-rich husk ash to increase the Si concentration in soil could effectively inhibit the absorption of As by rice. Field experiments were carried out to explore the regulation mechanism of Si-rich husk ash on As absorption by rice. Field experiment results showed that the addition of Si-ash significantly increased the porewater Si concentration by 866.0% compared with the control, which provided sufficient Si for rice growth and made Si play a dominant role in the competitive absorption of As. Meanwhile, Si-rich husk ash promoted the precipitation of  Fe plaque in soil and reduced the concentration of As in porewater by 20.3%. During this process, As released due to reductive dissolution of Fe plaque is re-retained. The formation of Fe plaque in rice roots plays a key role in inhibiting the transport of As to the shoot. Si-rich husk ash increased the root oxidation capacity by promoting the formation of aerated tissue, and the Fe concentration of Fe plaque on the rice root surface (DCB-Fe) increased by 47.3% compared with the control. The concentration of As in root surface Fe plaque (DCB-As) increased by 41.0% compared with the control. Si-rich husk ash provides sufficient Si for rice growth and restricts the absorption of As (III) by rice roots by down-regulating the expression of Si transporter Lsi1 and Lsi2 in rice roots. The results showed that Si-rich husk ash reduced the concentration of inorganic As in white rice by 29.1%, which is lower than the standard limit of GB 2762-2017 "Limit of Contaminants in Food of National Food Safety Standards". Through the field experiment, the study from the soil porewater, Fe plaque, and Si and As in straw and rice transportation system competition effect three aspects discusses the low-temperature combustion under the condition of the preparation of absorption of rice in Si-rich husk ash As a regulation function. The results showed that adding Si-rich husk ash at a ratio of 0.2% could effectively reduce As content in rice grains, providing an effective solution for the safe production and utilization of rice contaminated by As.