Abstract: To explore the improvement effect of different organic materials used as ameliorant, we added them to the pot paddy soil contaminated by Cd, to study their passivation effect on available Cd in soil. Under pot condition, we used different organic materials (calcined shell powder, shell powder without calcination, fermented cassava dregs, plant- derived organic fertilizer) and lime and“Tianshifu”passivator, to conduct single and combined application, and analyze their effects on Cd content in rice root system, straw and brown rice and the change of soil Cd combining state. The results showed that compared with CK, the pH value of soil treated with calcined shell powder 1.5% + organic fertilizer 1.5% significantly increased by 17.42%. At the same time, Cd content in brown rice decreased significantly by 49.04%. Single application of calcined shell powder 1.5% reduced Cd content of straw significantly by 93.8%, Cd content in roots decreased significantly by 54.2% with the application of shell powder without calcination 1.5%. In reducing the content of available Cd in soil, only“Tianshifu”passivator had significant effect, and the effect of other organic material was not significant. The effect of calcined shell powder and plant-source organic fertilizer on increasing the pH value of soil was obvious; the combination application of the two could improve the pH value of soil and decrease the content of Cd in brown rice, and the effect was better than that of single application; single application of shell powder could significantly reduce the content of Cd in straw and root system, and its effect was better than that of combined application.