Abstract: AMP loaded silica adsorbents (AMP/SiO₂) were synthesized by the rotary evaporation reducing pressure method and the crystallization method. A pressing/sintering method was used for the stable solidification of secondary solid wastes AMP-Cs/SiO₂ which was produced from the separation of Cs from simulated high level liquid waste. The properties of the solidified products were investigated. Without allophane, the immobilization percentage of Cs (Ⅰ) decreases to 40% when the temperature is more than 1 000 ℃. When adding allophane, the stable Cs₄Al₄Si₂₀O₄₈ crystalline phase is recrystallized, the Cs immobilization percentage is more than 96% and the compressive strength is higher than 7 MPa. The leachability of Cs (Ⅰ) from the deionized water (DW) is about 3×10^-5 g/(cm²•d) at 25 ℃.