Abstract: Cement solidification is the mainly technology used to treat low and intermediate level radioactive waste from nuclear power plants or nuclear facilities in China nowadays, among which the properties of cement paste as well as cement solidified radioactive waste forms are key focus. In this paper, the effect of mixing speed and mixing time on the fluidity of cement paste and the properties of cement solidified radioactive waste forms, such as 28 d compressive strength, pore structure, microstructure and anti leaching performance, were studied under different mixing conditions to simulate the low and intermediate radioactive waste by using ordinary Portland cement. The results show that the fluidity of cement slurry and the compressive strength of cement solidified waste form increase firstly and then decrease with the increase of mixing time (10-50 min), while the porosity and Sr²⁺ leaching rate of solidified body decrease with the increase of mixing time. Compared with the solidified body prepared by mixing for 10 min, the structure of 50 min solidified body is more compact. The compressive strength of solidified body prepared by the larger mixing speed is higher and the fluidity of slurry could be improved by raising the mixing speed during 30 min mixing time. However, the porosity of the solidified body prepared by mixing with large velocity is higher, as well as radionuclide leaching rate. As the mixing speed and mixing time will affect the fluidity of cement paste and the properties of cement solidified waste form, a series of experiments must be carried out before the cement solidification device is put into use, to determine the optimum mixing parameters satisfying the process requirements and the properties of the cement solidified waste form.