Abstract: The feasibility of immobilizing simulated radioactive slurry(SRS) by alkali- activated slag-clay minerals composite cement(AASCM) was studied under the experimental conditions. The results show that the flowability of the mixture of AASCM and SRS is highly dependent on the dosage of SRS and water cement ratio and the setting time is more dependent on temperature but less dependent on sorts of anions in the experiment. The application of AASCM in solidification engineering is suitable below 20℃. When cement-sand ratio is 1∶1 and water-cement ratio is 0.45, the flowability of the mixture meets the case of solidification engineering and the compressive strength of the waste forms containing 20% SRS meets the needs of GB 14569.1—93. The leaching rate of AASCM based waste forms is lower than that of ordinary Portland cement(OPC) based waste forms. Silicon fume can improve the workability of the mixture of AASCM and SRS and decrease the leaching rate of waste forms based on AASCM as well.