Abstract: In order to obtain the best growth period for rice leaf surface barrier application in the main soil types in Chongqing and improve the efficiency of leaf surface barrier technology in reducing Cd in rice seeds, ‘Hengfeng Youzhen Simiao’ seedling was selected as the test variety in Hechuan District (purple soil) and Qianjiang District (yellow soil), and ‘Chuge’ leaf surface barrier agent (rich Si type) was used for field comparative experiments. The results showed that only at the heading stage (T2) could the Cd content of rice seed (0.151 mg/kg) reduce to below the food safety limit, and only at the tillering stage (T1), tillering stage and heading stage (T3) could the Cd content of rice seed increase. All treatment groups in yellow soil showed the Cd reducing effect on rice seeds, but it was difficult to guarantee the safety of rice seeds (the Cd content of rice seeds was 0.210-0.245 mg/kg). The Cd reducing effect of spraying only at tillering stage (T1) was better than that at heading stage (T2). The soil Fe content is the key to the reduction efficiency of Cd in rice seed applied with leaf surface barrier at different growth stages, and a certain thickness of iron film on the root surface can block the transfer of Cd to the internal and aboveground tissues of rice roots. The yield of rice increased significantly by applying foliar barrier agent. The yield increases of T1-T3 in purple soil area and yellow soil area were 9.90%-12.25% and 5.06%-12.44%, respectively. The research shows that foliar barrier agents should only be applied at heading stage in purple soil area, while at tillering stage and heading stage in yellow soil areas, respectively. However, comprehensive control technology (VIP+n) should be adopted to ensure the safety of rice seeds. In addition, rice roots, stems and leaves have a strong ability to accumulate Cd, so it is recommended to remove rice roots from the field after rice harvest to increase the output flux of heavy metals in farmland soil.